Virtualization Blog

Discussions and observations on virtualization.

Tim Mackey is a community manager and evangelist for XenServer within the Citrix Open Source Business Office and is focused on server virtualization and cloud orchestration technical competencies. He joined Citrix through the Reflectent acquisition in 2006, and served as architect and developer for Citrix EdgeSight; an end user experience performance monitoring solution. In 2007, Mr. Mackey became technical product manager for the EdgeSight product line and then in 2009 product manager for the XenServer self-service virtualization components. Since that time, he has held various roles within the XenServer team, and speaks regularly on topics related to the design of large scale virtual environments.

XenServer Dundee Released

It was a little over a year ago when I introduced a project code named Dundee to this community. In the intervening year, we've had a number pre-release builds; all introducing ever greater capabilities into what I'm now happy to announce as XenServer 7. As you would expect from a major version number, XenServer 7 makes some rather significant strides forward, and defines a significant new capability.

Let's start first with the significant new capability. Some of you may have noted an interesting new security effort appear in upstream Xen a few years ago. Leading this effort was Bitdefender, and at the time it was known by the catchy title of "virtual machine introspection". This effort takes full advantage of the Intel EPT virtualization extensions to permit a true agentless anti-malware solution, where the anti-malware engine is placed in a service VM which is inaccessible from the guest VMs. XenServer 7 officially supports this technology with the Direct Inspect API set, and is platform ready for Bitdefender GravityZone HVI. For virtualization users, the combination of Direct Inspect and GravityZone HVI reduces the attack surface for malware by both removing in-guest agents, and by actively monitoring memory usage from the hypervisor to detect malicious memory accesses and flag questionable activity for remediation. When combined with support for Intel SMAP and PML, XenServer 7 offers significantly increased security compared to previous versions. Since secure operation extends to secure access to the host management APIs, XenServer 7 fully supports TLS 1.2, and can optionally mandate the use of TLS 1.2.

XenServer 7 extends the vGPU market initially defined in 2013 to include both increased scalability with NVIDIA GRID Maxwell M10 and the latest Intel Iris Pro virtual graphics. When combined, these vGPU extensions open the door to greater adoption of virtualized graphics by both increasing the number of GPU enabled VMs per host, as well as potentially removing the requirement for a dedicated GPU add-in card.

Operating virtual infrastructure at any level of scale requires an understanding of the overall health of the environment. While recent XenServer versions have included the ability to upload server status information to the free Citrix Insight Services, this operation was completely manual. With XenServer 7, we're introducing Health Check which is a proactive service which works in concert with Insight Services to monitor the operational health of a XenServer environment, and proactively alert you to any issues. The best part of Health Check is that it's completely free and open to any user of XenServer 7.

No major release would be complete without a requisite bump in performance, and XenServer 7 is no exception. Host memory limits have been bumped to 5TB per host, with a corresponding bump to 1.5TB per VM; OS willing of course. Host CPU count has been increased to 288 cores, and guest virtual CPU count has increased to 32; again OS willing. Disk scalability has also increased with support for up to 255 virtual block devices per VM and 4096 VBDs per host, all while supporting up to 20,000 VDIs per SR. Since XenServer often is deployed in Microsoft Windows environments, Active Directory support for role based authentication is a key requirement, and with XenServer 7, we've improved overall AD performance to support very large AD forests with a resulting improvement in login times.

 

XenServer 7 is available for download today, and can be obtained for free from the XenServer download page.

Recent Comments
Willem Boterenbrood
Congrats on the new release! We were waiting for it to arrive, finally XenServer support for Xeon v3/4 CPU masking and much more i... Read More
Tuesday, 24 May 2016 18:22
David Cottingham
Fixed -- thanks for catching that :-). Upgrades: please see http://docs.citrix.com/content/dam/docs/en-us/xenserver/xenserver-7-0... Read More
Tuesday, 07 June 2016 14:59
David Cottingham
DVSC is supported on 7.0. We're working on getting the downloads on citrix.com accessible.
Tuesday, 07 June 2016 15:07
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XenServer Administrators Handbook Published

Last year, I announced that we were working on a XenServer Administrators Handbook, and I'm very pleased to announce that it's been published. Not only have we been published, but based on the Amazon reviews to date we've done a pretty decent job. In part, I suspect that has a ton to do with the book being focused on what information you, XenServer administrators, need to be successful when running a XenServer environment regardless of scale or workload.

XenServer Administrators HandbookThe handbook is formatted following a simple premise; first you need to plan your deployment and second you need to run it. With that in mind, we start with exactly what a XenServer is, define how it works and what expectations it has on infrastructure. After all, it's critical to understand how a product like XenServer interfaces with the real world, and how its virtual objects relate to each other. We even cover some of the misunderstandings those new to XenServer might have.

While it might be tempting to go deep on some of this stuff, Jesse and I both recognized that virtualization SREs have a job to do and that's to run virtual infrastructure. As interesting as it might be to dig into how the product is implemented, that's not the role of an administrators handbook. That's why the second half of the book provides some real world scenarios, and how to go about solving them.

We had an almost limitless list of scenarios to choose from, and what you see in the book represents real world situations which most SREs will face at some point. The goal of this format being to have a handbook which can be actively used, not something which is read once and placed on some shelf (virtual or physical). During the technical review phase, we sent copies out to actual XenServer admins, all of whom stated that we'd presented some piece of information they hadn't previously known. I for one consider that to be a fantastic compliment.

Lastly, I want to finish off by saying that like all good works, this is very much a "we" effort. Jesse did a top notch job as co-author and brings the experience of someone who's job it is to help solve customer problems. Our technical reviewers added tremendously to the polish you'll find in the book. The O'Reilly Media team was a pleasure to work with, pushing when we needed to be pushed but understanding that day jobs and family take precedence.

So whether you're looking at XenServer out of personal interest, have been tasked with designing a XenServer installation to support Citrix workloads, clouds, or for general purpose virtualization, or have a XenServer environment to call your own, there is something in here for you. On behalf of Jesse, we hope that everyone who gets a copy finds it valuable. The XenServer Administrator's handbook is available from book sellers everywhere including:

Amazon: http://www.amazon.com/XenServer-Administration-Handbook-Successful-Deployments/dp/149193543X/

Barnes and Noble: http://www.barnesandnoble.com/w/xenserver-administration-handbook-tim-mackey/1123640451

O'Reilly Media: http://shop.oreilly.com/product/0636920043737.do

If you need a copy of XenServer to work with, you can obtain that for free from: http://xenserver.org/download

Recent Comments
Tobias Kreidl
A timely publication, given all the major recent enhancements to XenServer. It's packed with a lot of hands-on, practical advice a... Read More
Tuesday, 03 May 2016 03:37
Eric Hosmer
Been looking forward to getting this book, just purchased it on Amazon. Now I just need to find that mythical free time to read ... Read More
Friday, 06 May 2016 22:41
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XenServer Dundee Beta 3 Available

I am pleased to announce that Dundee beta 3 has been released, and for those of you who monitor Citrix Tech Previews, beta 3 corresponds to the core XenServer platform used for Dundee TP3. This third beta marks a major development milestone representing the proverbial "feature complete" stage. Normally when announcing pre-release builds, I highlight major functional advances but this time I need to start with a feature which was removed.

Thin Provisioned Block Storage Removed

While its never great to start with a negative, I felt anything related to removal of a storage option takes priority over new and shiny. I'm going to keep this section short, and also highlight that only the new thin provisioned block feature was removed and existing thin provisioned NFS and file based storage repositories will function as they've always done.

What should I do before upgrading to beta 3?

While we don't actively encourage upgrades to pre-release software, we do recognize you're likely to do it at least once. If you have built out infrastructure using thin provisioned iSCSI or HBA storage using a previous pre-release of Dundee, please ensure you migrate any critical VMs to either local storage, NFS or thick provisioned block storage prior to performing an upgrade to beta 3.

So what happened?

As is occasionally the case with pre-release software not all features which are previewed will make it to the final release; for any of a variety of reasons. That is of course one reason we provide pre-release access. In the case of the thin provisioned block storage implementation present in earlier Dundee betas, we ultimately found that it had issues under performance stress. As a result, we've made the difficult decision to remove it from Dundee at this time. Investigation into alternative implementations are underway, and the team is preparing a more detailed blog on future directions.

Beta 3 Overview

Much of difference between beta 2 and beta 3 can be found in some of the details. dom0 has been updated to a CentOS 7.2 userspace, the Xen project hypervisor is now 4.6.1 and the kernel is 3.10.96. Support for xsave and xrestor floating point instructions has been added, enabling guest VMs to utilize AVX instructions available on newer Intel processors. We've also added experimental support for the Microsoft Windows Server 2016 Tech Preview and the Ubuntu 16.04 beta.

Beta 3 Bug Fixes

Earlier pre-releases of Dundee had an issue wherein performing a storage migration of a VM with snapshots and in particular orphaned snapshots would result in migration errors. Work has been done to resolve this, and it would be beneficial for anyone taking beta 3 to exercise storage motion to validate if the fix is complete.

One of the focus areas for Dundee is to improve scalability, and as part of that we've uncovered some situations where overall reliability wasn't what we wanted. An example of such a situation, which we've resolved, occurs when a VM with a very large number of VBDs is running on a host, and a XenServer admin requests the host to shutdown. Prior to the fix, such a host would become unresponsive.

The default logrotate for xensource.log has been changed to rotate at a 100MB in addition to daily. This change was done as on very active systems excessive disk consumption could result in the prior configuration.

Download Information

You can download Dundee beta.3 from the Preview Download page (http://xenserver.org/preview), and any issues found can be reported in our defect database (https://bugs.xenserver.org).     

Recent Comments
Tobias Kreidl
Given the importance of thin provisioning for block-based storage devices, I'm sure that Citrix will find a solution. It takes mak... Read More
Wednesday, 16 March 2016 03:08
Tim Mackey
@Tobias Thanks. We haven't given up on thin provisioned block at all. We're already down a different path which is looking promis... Read More
Wednesday, 16 March 2016 13:32
Gianni D
Not sure if this was by design but the Beta 3 XenCenter won't allow vm migration on older versions of XenServer. Option doesn't e... Read More
Wednesday, 16 March 2016 04:26
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XenServer Dundee Beta.2 Available

With 2015 quickly coming to a close, and 2016 beckoning, it's time to deliver a holiday present to the XenServer community. Today, we've released beta 2 of project Dundee. While the lag between beta 1 in September and today has been a bit longer than many would've liked, part of that lag was due to the effort involved in resolving many of the issues reported. The team is confident you'll find both beta 2 and Steve Wilson's blog affirming Citrix's commitment to XenServer to be a nice gift. As part of that gift, we're planning to have a series of blogs covering a few of the major improvements in depth, but for those of you who like the highlights - let's jump right in!

CPU leveling

XenServer has supported for many years the ability to create resource pools with processors from different CPU generations, but a few years back a change was made with Intel CPUs which impacted our ability mix the newest CPUs with much older ones. The good news is that with Dundee beta.2, that situation should be fully resolved, and may indeed offer some performance improvements. Since this is an area where we really need to get things absolutely correct, we'd appreciate anyone running Dundee to try this out if you can and report back on successes and issues.

Increased scalability

Modern servers keep increasing their capacity, and not only do we need to keep pace, but we need to ensure users can create VMs which mirror the capacity of a physical machines. Dundee beta.2 now supports up to 512 physical cores (pCPUs), and can create guest VMs with up to 1.5 TB RAM. Some of you might ask about increasing vCPU limits, and we've bumped those up to 32 as well. We've also enabled Page Modification Logging (PML) in the Xen Project hypervisor as a default. The full design details for PML are posted in the Xen Project Archives for review if you'd like to get into the weeds of why this is valuable. Lastly we've bumped the kernel version to 3.10.93.

New SUSE templates

SUSE have released version 12 SP1 for both (SUSE Linux Enterprise Server) SLES and (SUSE Linux Enterprise Desktop) SLED, both of which are now supported templates in Dundee.

Security updates

Since Dundee beta.1 was made available in late September, a number of security hotfixes for XenServer 6.5 SP1 have been released. Where valid, those same security patches have been applied to Dundee and are included in beta.2.

Download Information

You can download Dundee beta.2 from the Preview Download page (http://xenserver.org/preview), and any issues found can be reported in our defect database (https://bugs.xenserver.org).     

Recent Comments
Tobias Kreidl
Great news, Tim! Is it correct the 32 VCPUs are now supported for both Linux and Windows guests (where of course supported by the ... Read More
Tuesday, 22 December 2015 04:43
Tim Mackey
Thanks, Tobias. This would be 32 vCPUS for both PV and HVM. I *think* we're at 254 VDIs in Dundee, but with the caveat things mi... Read More
Thursday, 24 December 2015 01:59
Tim Mackey
N3ST, We never commit to a stable upgrade path from any preview version to a final release. It's been known to work in previous ... Read More
Thursday, 24 December 2015 02:02
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XenServer Dundee Beta 1 Available

We are very pleased to make the first beta of XenServer Dundee available to the community. As with all pre-release downloads, this can be found on the XenServer Preview page. This release does include some potential commercial features, and if you are an existing Citrix customer you can access those features using the XenServer Tech Preview. It's also important to note that a XenServer host installed from the installer obtained from either source will have identical version number and identical functionality. Application of a Tech Preview license unlocks the potential commercial functionality. So with the "where do I get Dundee beta 1" out of the way, I bet you're all interested in what the cool bits are, and what things might be worth paying attention to. With that in mind, here are some of the important platform differences between XenServer 6.5 SP1 and Dundee beta 1.

Updated dom0

The control domain, dom0, has undergone some significant changes. Last year we moved to a 64 bit control domain with a 3.10 kernel as part of our effort to increase overall performance and scalability. That change allowed us to increase VM density to 1000 VMs per host while making some significant gains in both storage and network performance. The dom0 improvements continue, and could have a direct impact on how you manage a XenServer.

CentOS 7

dom0 now uses CentOS 7 as it's core operating system, and along with that change is a significant change in how "agents" and some scripts run. CentOS 7 has adopted systemd, and by extension so too has XenServer. This means that shell scripts started at system initialization time will need to change to follow the unit and service definition model specified for systemd.

cgroups for Control Isolation

Certain xapi processes have been isolated into Linux control groups. This allows for greater system stability under extreme resource pressure which has created a considerably more deterministic model for VM operations. The most notable area where this can be observed is under bootstorm conditions. In XenServer 6.5 and prior, starting large numbers of VMs could result in start operations being blocked due to resource contention which could result in some VMs taking significantly longer to start than others. With xapi isolation into cgroups, VM start operations no longer block as before resulting in VM start times being much more equitable. This same optimization can be seen in other VM operations such as when large quantities of VMs are shutdown.

RBAC Provider Changes

XenServer 6.5 and prior used an older version of Likewise to provide Active Directory. Likewise is now known as Power Broker, and XenServer is using the Power Broker Identity Services to provide authentication for RBAC. This has improved performance, scale and reliability, especially for complex or nested directory structures. Since RBAC is core to delegated management of a XenServer environment, we are particularly interested in feedback on any issues users might have with RBAC in Dundee beta 1.

dom0 Disk Space Usage

In XenServer 6.5 and prior, dom0 disk space was limited to 4GB. While this size was sufficient for many configurations, it was limiting for more than a few of you. As a result we've split dom0 disk into three core partitions; system, log and swap. The system partition is now 18GB which should provide sufficient for some time to come. This also means that the overall install space required for XenServer increases from 8GB to 46GB. As you can imagine, given the importance of this major change, we are very interested to learn of any situations where this change prevents XenServer from installing or upgrading properly.

Storage Improvements

Having flexible storage options is very important to efficient operation of any virtualization solution. To that end, we've added in support for three highly requested storage improvements; thin provisioned block storage, NFSv4 and FCoE.

Thin Provisioned Block Storage

iSCSI and HBA block storage can now be configured to be thinly provisioned. This is of particular value to those users who provision guest storage with a high water mark expecting that some allocated storage won't be used. With XenServer 6.5 and prior, the storage provider would allocate the entire disk space which could result in a significant reduction in storage utilization which in turn would increase the cost of virtualization. Now block storage repositories can be configured with an initial size and an increment value. Since storage is critical in any virtualization solution, we are very interested in feedback on this functional change.

FCoE

Fibre Channel over Ethernet is protocol which allows Fibre Channel traffic to travel over standard ethernet networks. XenServer now is able to communicate with FCoE enabled storage solutions, and can be configured at install time to allow boot from SAN with FCoE. If you are using FCoE in your environment, we are very interested in learning both any issues as well as learning what CNA you used during your tests.

Operational Improvements

Many additional system level improvements have been made for Dundee beta 1, but the following highlight some of the operational improvements which have been made.

UEFI Boot

XenServer 6.5 and prior required legacy BIOS mode to be enabled on UEFI based servers. With Dundee beta 1, servers with native UEFI mode enabled should now be able to install and run XenServer. If you encounter a server which fails to install or boot XenServer in UEFI mode, please provide server details when reporting the incident.

Automatic Health Check

XenServer can now optionally generate a server status report on a schedule and automatically upload it to Citrix Insight Services (formerly known as TaaS). CIS is a free service which will then perform the analysis and report on any health issues associated with the XenServer installation. This automatic health check is in addition to the manual server status report facility which has been in XenServer for some time.

Improved Patch Management in XenCenter

Application of XenServer patches through XenCenter has become easier. The XenCenter updates wizard has been rewritten to find all patches available on Citrix’s support website, rather than ones that have been installed on other servers. This avoids missing updates, and allows automatic clean-up of patches files at the end of the installation.

Why Participate in the Beta Program

These platform highlights speak to how significant the engineering effort has been to get us to beta 1. They also overshadow some other arguably core items like a move to the Xen Project Hypervisor 4.6, host support for up to 5TB of host RAM or even Windows guest support for up to 1TB RAM. What they do show is our commitment to the install base and their continued adoption of XenServer at scale. Last year we ran an incredibly successful prerelease program for XenServer Creedence, and its partly through that program that XenServer 6.5 is as solid as it is. We're building on that solid base in the hopes that Dundee will better those accomplishments, and we're once again requesting your help. Download Dundee. Test it in your environment. Push it, and let us know how it goes. Just please be aware that this is prerelease code which shouldn't be placed in production and that we're not guaranteeing you'll ever be able to upgrade from it.

Download location: http://xenserver.org/prerelease

Defect database: https://bugs.xenserver.org

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Recent Comments
Ezequiel Mc Govern
Ceph SR suppport is On the roadmap?
Tuesday, 22 September 2015 19:15
Tim Mackey
Dan, I'll need to check the local SR file system, but think its still ext3. Local storage is an important use case, so I'm curiou... Read More
Monday, 28 September 2015 15:31
Senol Colak
Hi Tim, simple, ext3 is not supporting SSD drives with TRIM. You need ext4 to get TRIM support. After the successfull installatio... Read More
Thursday, 01 October 2015 13:19
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XenServer Dundee Alpha.3 Available

The XenServer team is pleased to announce the availability of the third alpha release in the Dundee release train. This release includes a number of performance oriented items and includes three new functional areas.

  • Microsoft Windows 10 driver support is now present in the XenServer tools. The tools have yet to be WHQL certified and are not yet working for GPU use cases, but users can safely use them to validate Windows 10 support.
  • FCoE storage support has been enabled for the Linux Bridge network stack. Note that the default network stack is OVS, so users wishing to test FCoE will need to convert the network stack to Bridge and will need to be aware of the feature limitations in Bridge relative to OVS.
  • Docker support present in XenServer 6.5 SP1 is now also present in Dundee

Considerable work has been performed to improve overall I/O throughput on larger systems and improve system responsiveness under heavy load. As part of this work, the number of vCPUs available to dom0 have been increased on systems with more than 8 pCPUs. Early results indicate a significant improvement in throughput compared to Creedence. We are particularly interested in hearing from users who have previously experienced responsiveness or I/O bottlenecks to look at Alpha.3 and provide their observations.

Dundee alpha.3 can be downloaded from the pre-release download page.     

Recent Comments
Sam McLeod
Hi Tim, Great to hear about the IO! As you know, we're very IO intensive and have very high speed flash-only iSCSI storage. I'll ... Read More
Thursday, 20 August 2015 01:50
Tim Mackey
Excellent, Sam. I look forward to hearing if you feel we've moved in the right direction and by how much.
Thursday, 20 August 2015 02:08
Chris Apsey
Has any testing been done with 40gbps NICS? We are considering upgrading to Chelsio T-580-LP-CRs, and if the ~24gbps barrier has ... Read More
Thursday, 20 August 2015 19:25
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Dundee Alpha 2 Released

I am pleased to announce that today we have made available the second alpha build for XenServer Dundee. For those of you who missed the first alpha, it was focused entirely on the move to CentOS 7 for dom0. This important operational change is one long time XenServer users and those who have written management tooling for XenServer should be aware of throughout the Dundee development cycle. At the time of Alpha 1, no mention was made for feature changes, and with Alpha 2 we're going to talk about some features. So here are some of the important items to be aware of.

Thin Provisioning on block storage

For those who aren't aware, when a XenServer SR is using iSCSI or an HBA, the virtual disks have always consumed their entire allocated space regardless of how utilized the actual virtual disk was. With Dundee we now have full thin provisioning for all block storage independent of storage vendor. In order to take advantage of this, you will need to indicate during SR creation that thin provisioning is required. You will also be given the opportunity to specify the default vdi allocation which allows users to optimize vdi utilization against storage performance. We do know about a number of areas still needing attention, but are providing early access such that the community can further identify issues our testing hasn't yet encountered.

NFS version 4

While a simple enhancement, this was identified as a priority item during the Creedence previews last year. We didn't really have the time then to fully implement it, but as of Dundee Alpha 2 you can specify NFS 4 for SR creation in XenCenter.

Intel GVT-d

XenServer 6.5 SP1 introduced support for Intel GVT-d graphics in Haswell and Broadwell chips. This support has been ported to Dundee and is now present in Alpha 2. At this point GPU operations in Dundee should have feature parity to XenServer 6.5 SP1.

CIFS for virtual disk storage

For some time we've had CIFS as an option for ISO storage, but lacked it for virtual disk storage. That has been remedied and if you are running CIFS you can now use it for all your XenServer storage needs.

Changed dom0 disk size

During installation of XenServer 6.5 and prior, a 4GB partition is created for dom0 with an additional 4GB partition created as a backup. For some users, the 4GB partition was too limiting, particularly if remote SYSLOG wasn't used or when third party monitoring tools were installed in dom0. With Dundee we've completely changed the local storage layout for dom0, and this has significant implications for all users wishing to upgrade to Dundee.

New layout

The new partition layout will consume 46GB from local storage. If there is less than 46 GB available, then a fresh install will fail. The new partition layout will be as follows:

  • 512 MB UEFI boot partition
  • 18 GB dom0 partition
  • 18 GB backup partition
  • 4 GB logs partition
  • 1 GB SWAP partition

As you can see from this new partition layout that we've separated logs and SWAP out of the main operating partition, and that we're now supporting UEFI boot.

Upgrades

During upgrade, if there is at least 46 GB available, we will recreate the partition layout to match that of a fresh install. In the event 46GB isn't available, we will shrink the existing dom0 partition from 4 GB to 3.5 GB and create the 512 MB UEFI boot partition.

Downloading Alpha 2

 

Dundee Alpha 2 is available for download from xenserver.org/prerelease

Recent Comments
Tim Stephenson
46Gb+ seems very large for Dom0 :/ We're running XenServer on a set of Dell Poweredge R630's s equipped with dual 16Gb SD card bo... Read More
Tuesday, 14 July 2015 20:17
Tim Mackey
It's not 46GB for dom0, but 46GB for all storage dedicated to XenServer itself (dom0 is only 18GB). I hear you about the SD card ... Read More
Tuesday, 14 July 2015 20:26
Tobias Kreidl
First off, this is fantastic news, regarding what's mentioned (NFSv4, thin provisioning on LVM, bigger partition space, CIFS stora... Read More
Tuesday, 14 July 2015 20:45
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Preview of XenServer Administrators Handbook

Administering any technology can be both fun and challenging at times. For many, the fun part is designing a new deployment while for others the hardware selection process, system configuration and tuning and actual deployment can be a rewarding part of being an SRE. Then the challenging stuff hits where the design and deployment become a real part of the everyday inner workings of your company and with it come upgrades, failures, and fixes. For example, you might need to figure out how to scale beyond the original design, deal with failed hardware or find ways to update an entire data center without user downtime. No matter how long you've been working with a technology, the original paradigms often do change, and there is always an opportunity to learn how to do something more efficiently.

That's where a project JK Benedict and I have been working on with the good people of O'Reilly Media comes in. The idea is a simple one. We wanted a reference guide which would contain valuable information for anyone using XenServer - period. If you are just starting out, there would be information to help you make that first deployment a successful one. If you are looking at redesigning an existing deployment, there are valuable time-saving nuggets of info, too. If you are a longtime administrator, you would find some helpful recipes to solve real problems that you may not have tried yet. We didn't focus on long theoretical discussions, and we've made sure all content is relevant in a XenServer 6.2 or 6.5 environment. Oh, and we kept it concise because your time matters.

I am pleased to announce that attendees of OSCON will be able to get their hands on a preview edition of the upcoming XenServer Administrators Handbook. Not only will you be able to thumb through a copy of the preview book, but I'll have a signing at the O'Reilly booth on Wednesday July 22nd at 3:10 PM. I'm also told the first 25 people will get free copies, so be sure to camp out ;)

Now of course everyone always wants to know what animal which gets featured for the book cover. As you can see below, we have a bird. Not just any bird mind you, but a xenops. Now I didn't do anything to steer O'Reilly towards this, but find it very cool that we have an animal which also represents a very core component in XenServer; the xenopsd. For me, that's a clear indication we've created the appropriate content, and I hope you'll agree.

 

             

Recent Comments
prashant sreedharan
cool ! cant wait to get my hands on the book :-)
Tuesday, 07 July 2015 19:32
Tobias Kreidl
Congratulations, Tim and Jesse, as an update in this area is long overdue and in very good hands with you two. The XenServer commu... Read More
Tuesday, 07 July 2015 19:42
JK Benedict
Ah, Herr Tobias -- Danke freund. Danke fur ihre unterstutzung! Guten abent!
Thursday, 23 July 2015 09:26
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Security bulletin covering VENOM

Last week a vulnerability in QEUM was reported with the marketing name of "VENOM", but which is more correctly known as CVE-2015-3456.  Citrix have released a security bulletin covering CVE-2015-3456 which has been updated to include hotfixes for XenServer 6.5, 6.5 SP1 and XenServer 6.2 SP1.

Learning about new XenServer hotfixes

When a hotfix is released for XenServer, it will be posted to the Citrix support web site. You can receive alerts from the support site by registering at http://support.citrix.com/profile/watches and following the instructions there. You will need to create an account if you don't have one, but the account is completely free. Whenever a security hotfix is released, there will be an accompanying security advisory in the form of a CTX knowledge base article for it, and those same KB articles will be linked on xenserver.org in the download page.

Patching XenServer hosts

XenServer admins are encouraged to schedule patching of their XenServer installations at their earliest opportunity. Please note that this bulletin does impact XenServer 6.2 hosts, and to apply the patch, all XenServer 6.2 hosts will first need to be patched to service pack 1 which can be found on the XenServer download page

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XenServer 6.5 SP1 Released

Wait, another XenServer release? Yes folks, there is no question we've been very busy improving upon XenServer over the past year, and the pace is quite fast. In case you missed it, we released XenServer 6.5 in January (formerly known as Creedence). Just a few weeks ago I announced and made available pre-release binaries for Dundee, and now we've just announced availability at Citrix Synergy of the first service pack for XenServer 6.5. Exciting times indeed.

What's in XenServer 6.5 SP1

I could bury the lead talk about hot fixes and roll-ups (more on that later), but the real value for SP1 is in the increased capabilities. Here are the lead items for this service pack:

  1. The Docker work we previewed in January at FOSDEM and later on xenserver.org is now available. If you've been using xscontainer in preview form, it should upgrade fine, but you should back up any VMs first. Completion of the Docker work also implies that CoreOS 633.1.0 is also an officially supported operating system with SP1. Containers deployed in Unbuntu 14.04 and RHEL, CentOS, and Oracle Enterprise Linux 7 and higher are supported.
  2. Adoption of LTS (long term support) guest support. XenServer guest support has historically required users of guest operating system to wait for XenServer to adopt official support for point releases in order to remain in a supported configuration. Starting with SP1, all supported operating systems can be upgraded within their major version and still retain "supported" status from Citrix support. For example, if a CentOS 6.6 VM is deployed, and the CentOS project subsequently releases CentOS 6.7, then upgrading that VM to CentOS 6.7 requires no changes to XenServer in order to remain a supported configuration.
  3. Intel GVT-d support for GPU pass through for Windows guests. This allows users of Xeon E3 Haswell processors to use the embedded GPU in those processors within a Windows guest using standard Intel graphics drivers.
  4. NVIDIA GPU pass though to Linux VMs allowing OpenGL and CUDA support for these operating systems.
  5. Installation of supplemental packs can now be performed through XenCenter Update. Note that since driver disks are only a special case of a supplemental pack, driver updates or installation of drivers not required for host installation can now also be performed using this mechanism
  6. Virtual machine density has been increased to 1000. What this means is that if you have a server which can reasonably be expected to run 1000 VMs of a given operating system, then using XenServer you can do so. No changes were made to the supported hardware configuration to accommodate this change.

Hotfix process

As with all XenServer service packs, XenServer 6.5 SP1 contains a rollup of all existing hot fixes for XenServer 6.5. This means that when provisioning a new host, your first post-installation step should be to apply SP1. It's also important to call out that when a service pack is released, hotfixes for the prior service pack level will no longer be created within six months. In this case, hotfixes for XenServer 6.5 will only be created through November 12th and following that point hotfixes will only be created for XenServer 6.5 SP1. In order for the development teams to streamline that transition, any defects raised for XenServer 6.5 in bugs.xenserver.org should be raised against 6.5 SP1 and not base 6.5.

Where to get XenServer 6.5 SP1

 

Downloading XenServer 6.5 SP1 is very easy, simply go to http://xenserver.org/download and download it!     

Recent Comments
Tobias Kreidl
Very nice! One quick question: It we want to work with both XS 6.5 SP1 and the technical pre-release Dundee version, is there or w... Read More
Tuesday, 12 May 2015 18:28
Tobias Kreidl
Found out these are 99% compatible (thanks, Andy!), so either should work fine. The Dundee XenCenter release shows a slightly newe... Read More
Wednesday, 13 May 2015 09:39
Stephen Turner
Hi, Tobias. Dundee XenCenter already includes all the changes in 6.5SP1, so you can just use that one to manage everything (everyt... Read More
Wednesday, 13 May 2015 08:23
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Introducing XenServer Dundee

It's spring time and after a particularly brutal winter here in Boston, I for one am happy to see the signs of spring. Grass and greenery, flowers budding, and warmer days all speak to good things coming. It's also time to unveil the next major XenServer project, code named Dundee. As with Creedence last year, we're going to be giving early access to a major new version of XenServer well in advance of its release. This project will have its share of functional improvements, and a few new features, but just like last year we're going to start with the platform and progress slowly.

CentOS 7 dom0

During the Creedence pre-release program, many commented on "Why CentOS 5.x? - CentOS 6 has been out for a while, and 7 is fresh". The answer to that question was pretty simple. We knew what userspace looked like with CentOS 5.x, and our users understood how to manage a CentOS 5.x system. CentOS 5 was being supported upstream until 2017, so there was no risk of us having something unsupported. Moving to CentOS 6.5 would've been a valid option if we didn't already plan on moving to CentOS 7, but we didn't want to change dom0 just to change it again in a years time. Plus if you recall, we took on quite a bit with Creedence in 2014.

So we're now a year later, and CentOS 7 makes perfect sense for dom0. Not only are there a few more upstream patches available, but Linux admins are now more comfortable with the changes in management paradigm. It's also those changes in paradigm which may present issues for you our users, and why this first alpha is all about validation. If you manage XenServer from a tool which uses the xapi SDK, then you shouldn't really experience too many problems. On the other hand, if you've favorite scripts, or tweaks you've made to configuration files, then you could be in for some extra work.

Now is also a perfect time to remind everyone that when you "upgrade" a XenServer, it's not an in place upgrade. We preserve the configuration files we know about, and then dom0 is reimaged. Any third party packages you have installed, custom scripts, and manual configuration changes have a good chance of being lost unless you've backed them up. In this case, with a move to CentOS 7, it's also possible that those items will need to be reworked to some degree.

Understanding the pre-release process

All pre-release downloads will be on our pre-release download page. We'll be providing new tagged builds every few weeks, and generally as we achieve internal milestones. With each build, we'll call out something which you as an interested participant in XenServer Dundee should be looking at. Issues encountered can be logged in the incident database at https://bugs.xenserver.org. Since we've more than one version of XenServer covered in the incident database, please make certain you report Dundee issues under the "Dundee" version. Of course there is no guarantee we'll be able to resolve what you find, but we do want to know about it. With this first alpha, we’re interested in the “big issues” you may hit, i.e. areas which would block usage of features or functionality or cases where there is a major impact. These are really useful as the product develops and matures during the alpha stage. If you are developing something for XenServer, we invite you to ask your questions on the development mailing list, but do remember it's not a product support list.

Lastly, while we're in a pre-release period, its also likely you may eventually encounter functionality which may form part of a commercial edition. At this point we're not committing to what functionality will actually ship, when it might ship, or if it'll require a commercial license. I understand that might be concerning, but it shouldn't be. If something is destined for a commercial edition, you'll see it "commercialized" in a Citrix Tech Preview before we release. Historically we're many months away from when a Tech Preview might happen, so right now the most important thing is to focus on the changes we're interested in your feedback on today - everything to do with a CentOS 7 dom0.

Download Dundee alpha.1: http://xenserver.org/preview

Recent Comments
Tobias Kreidl
Keep the XenServer evolution rolling! Great to see this initiative so soon after Creedence was released.
Tuesday, 28 April 2015 23:37
Tobias Kreidl
Is there a separate document available with just the release notes?
Wednesday, 29 April 2015 16:09
Martin Kralicek
Yes, the document/page containing roadmap or list of new features would be so good to have I am looking forward for next release.... Read More
Thursday, 07 May 2015 13:09
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Citrix Joins OpenStack Foundation

Some of you might have noticed that Citrix joined the OpenStack Foundation yesterday and may be wondering what this means for two key technologies I've been closely involved with; Apache CloudStack and XenServer. The first, and arguably most important thing to note is that as Steve Wilson has stated, we're embracing both OpenStack and CloudStack to help further innovation. Nand Mulchandani also highlights that a culture of “anyness” is a core part of Citrix. With all the noise in the market about the various IaaS cloud solutions, supporting user choice is an important point to be clear on. So with that as backdrop, what does this really mean?

The XenServer Perspective on OpenStack

As I mentioned in my blog about OpenStack Summit, I really want XenServer to be a first class citizen within OpenStack. I tried to further that objective through submission of presentations to OpenStack Summit, but if you look at the schedule you'll note that no XenServer related talks were accepted. That's unfortunate, and really speaks to the challenge we face within a community when we're not the obvious or default choice. Obviously we can raise our profile through contributions and simply showing up at OpenStack events, but there is also a pretty important and easy thing we can change.

When a vendor evaluates a technology, they look at the ecosystem around it. OpenStack technology has a ton of buzz. If you look on job boards, you'll see many postings for OpenStack positions. If you search for cloud technologies, key supporters of OpenStack will be listed. Importantly, when selecting a technology suite, you'll look at who supports their technology with the suite and use them in your short list. Until today, it was unclear if Citrix actively supported the use of XenServer within OpenStack. Our joining the OpenStack Foundation is one way of signaling to those who prefer OpenStack that Citrix is supportive of their efforts. So if you've been quietly using XenServer in an OpenStack environment, I want to learn more about it. I want to learn what works, and where the pain points are so they might be addressed. If you've ever questioned if production support for XenServer when used with OpenStack could be supported, the answer is yes, and here's a link to buy support (hard sell over)!

The XenServer Perspective on CloudStack

For those of you who have adopted XenServer for your CloudStack clouds, nothing has changed and you should feel nothing change. XenServer will remain a first class citizen in CloudStack, and we'll continue to improve all aspects of XenServer operation within CloudStack such that XenServer remains an obvious choice. You'll continue to see XenServer content proposed to CloudStack events, and I hope you'll continue to accept those talks. I promise to continue to work on cool things like the Packer work I presented at CloudStack Day Austin which showed a method to migrate legacy infrastructure running on XenServer to a CloudStack cloud powered by XenServer; all without the users even noticing the migration happened. My hope is that the OpenStack community will want some of those same cool things, but that will take time and can't be forced.

So in the end this really isn't a commentary about which cloud solution is better, but a case of allowing customer choice. OpenStack has mindshare, and it only makes sense for Citrix and its technology suite to have a seat at the table. With Citrix openly supporting its technologies when deployed with OpenStack, everyone has the freedom to choose which solution works best.     

Recent Comments
Sebastian
I would like to see XenServer in OpenStack. At the moment we use XenServer on all our servers but we are looking for a solution li... Read More
Tuesday, 28 April 2015 08:07
Tim Mackey
Sebastian, XenServer is supported through the use of the "xapi" Nova driver in OpenStack, and also within CloudStack. Both OpenS... Read More
Tuesday, 28 April 2015 13:29
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XenServer at OpenStack Summit

It's coming up on time for OpenStack Summit Vancouver where OpenStack developers and administrators will come together to discuss what it means and takes to run a successful cloud based on OpenStack technologies. As in past Summits, there will be a realistic focus on KVM based deployments due to KVM, or more precisely libvirt, having "Group A" status within the compute driver test matrix. XenServer currently has "Group B" status, and when you note that the distinction between A and B really boils down to which can gate a commit, there is no logical reason why XenServer shouldn't be a more prevalent option.

Having XenServer be thought of as completely appropriate for OpenStack deployments is something I'm looking to increase, and I'm asking for your help. The OpenStack Summit organizers want to ensure the content matches the needs of the community. In order to help ensure this, they invite their community to vote on the potential merit of all proposals. This is pretty cool since it helps ensure that the audience gets what they want, but it also makes it a bit harder if you're not part of the "mainstream". That's where I reach out to you in the XenServer community. If you're interested in seeing XenServer have greater mindshare within OpenStack, then please vote for one or both of my submissions. If your personal preference is for another cloud solution, I hope that you agree with me that increasing our install base strengthens both our community and XenServer, and will still take the time to vote. Note that you may be required to create an account, and that voting closes on February 23rd.

Packaging GPU intensive applications for OpenStack

If you'd like to see the GPU capabilities of XenServer materialize within OpenStack, please vote for this session using this link: https://www.openstack.org/vote-vancouver/Presentation/packaging-gpu-intensive-applications-for-openstack. The session will encompass some of the Packer work I've been involved with, and also the GPU work XenServer is leading on with NVIDIA.

Avoiding the 1000 dollar VM in your first cloud

This session covers the paradigm shifts involved when an organization decides to move from traditional data center operations to "the could". Since this is a technology talk, it's not strictly XenServer orientated, but XenServer examples are present. To vote for this session, use this link: https://www.openstack.org/vote-vancouver/Presentation/avoiding-the-1000-dollar-vm-in-your-first-cloud

Thank you to everyone who decides to support this effort.

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xenserver.org gets a refresh

Now that Creedence has shipped as XenServer 6.5, and we've even addressed some early issues with hotfixes (in record time no less), it was time to give xenserver.org a bit of an update as well. All of the content you've known to be on xenserver.org is still here, but this face lift is the first in a series of changes you'll see coming over the next few months.

Our Role

The role of xenserver.org will be shifting slightly from what we did in 2014 with an objective that by the end of 2015 it is the portal virtualization administrators use to find the information they need to be successful with XenServer. That's everything from development blogs, pre-release information, but also deeper technical content. Not everything will be hosted on xenserver.org, but we'll be looking for the most complete and accurate content available. Recognizing that commercial support is a critical requirement for production use of any technology, if we list a solution we'll also state clearly if its use is commercially supportable by Citrix or whether it could invalidate your support contract. In the end, this about successfully running a XenServer environment, so some practices presented might not be "officially sanctioned" and tested to the same level as commercially supported features, but are known by the community to work.

Community Content

The new xenserver.org will also have prominent community content. By its very nature, XenServer lives in a data center ecosystem populated by third party solutions. Some of those solutions are commercial in nature, and because commercial solutions should always retain "supported environment" status for a product, we've categorized them all under the "Citrix Ready" banner. Details on Citrix Ready requirements can be found on their FAQ page. Other solutions can be found within open source projects. We on the XenServer team are active in many, and we're consolidating information you'll need to be successful with various projects under the "Community" banner.

Commercial Content

We've always promoted commercial support on xenserver.org, and that's not changing. If anything, you'll see us bias a bit more towards promoting both support and some of the premium features within XenServer. After-all there is only one XenServer and the only difference between the installer you get from xenserver.org and from citrix.com is the EULA. Once you apply a commercial license, or use XenServer as part of an entitlement within XenDesktop, you are bound by the same commercial EULA regardless of where the installation media originated.

Contributing Content

Public content contributions to xenserver.org have always been welcome, and with our new focus on technical information to run a successful XenServer installation, we're actively seeking more content. This could be in the form of article or blog submissions, but I'm willing to bet the most efficient way will be just letting us know about content you discover. If you find something, tweet it to me @XenServerArmy and we'll take a look at the content. If it is something we can use, we'll write a summary blog or article and link to it. Of course before that can happen we'll need to verify if the content could create an unsupported configuration and warn users upfront if it does.

 

What kind of content are we looking for? That's simple, anything you find useful to manage your XenServer installation. It doesn't matter how big or small that might be, or what tooling you have in place, if it helps you to be productive, we think that's valuable stuff for the community at large.     

Recent Comments
Tobias Kreidl
Tim, This is a great new direction and the planned diverse content is a welcome change. Many of the more technical articles have b... Read More
Thursday, 19 February 2015 19:15
Tim Mackey
I'm not certain what you mean by "font +/-". I used Chrome to scale the site and the fonts scaled as they should.
Wednesday, 25 February 2015 15:39
Tim Mackey
Thanks. I'm seeing something similar, and am curious if for you its just the homepage, or other pages?
Wednesday, 25 February 2015 15:38
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XenServer at FOSDEM

Having just released Creedence as XenServer 6.5, 2015 has definitely started off with a bang. In 2014 the focus for XenServer was on a platform refresh, and creating a solid platform for future work. For me, 2015 is about enabling the ecosystem to be successful with XenServer, and that's where FOSDEM comes in. For those unfamiliar with FOSDEM, it's the Free and Open Source Developers European Meeting, and many of the most influential projects will have strong representation. Many of those same projects have strong relationships with other hypervisors, but not necessarily with XenServer. For those projects, XenServer needs to demonstrate its relevance, and I hope through a set of demos within the Xen Project stand to provide exactly that.

Demo #1 - Provisioning Efficiency

XenServer is a hypervisor, and as such is first and foremost a provisioning target. That means it needs to work well with provisioning solutions and their respective template paradigms. Some of you may have seen me present at various events on the topic of hypervisor selection in various cloud provisioning tools. One of the core workflow items for all cloud solutions is the ability to take a template and provision it consistently to the desired hypervisor. In Apache CloudStack with XenServer for example, those templates are VHD files. Unfortunately, XenServer by default exports XVA files, not native VHD; which makes the template process for CloudStack needlessly difficult.

This is where a technology like Packer comes in. Some of the XenServer engineers have been working on a Packer integration to support Vagrant. That's cool, but I'm also looking at this from the perspective of other tools and so will be showing Packer creating a CentOS 7 template which could be used anywhere. That template would then be provisioned and as part of the post-provisioning configuration management become a "something" with the addition of applications.

Demo #2 - Application Containerization

Once I have my template from Packer, and have provisioned it into a XenServer 6.5 host, the next step is application management. For this I'm going to use Ansible to personalize the VM, and to add in some applications which are containerized by Docker. There has been some discussion in the marketplace about containers replacing VMs, and I really see proper use of containers as being efficient use of VMs not as a replacement for a VM. Proper container usage is really proper application management, and understanding when to use which technology. For me this means that a host is a failure point which contains VMs. A VM represents a security and performance wrapper for a given tenant and their applications. Within a VM applications are provisioned, and where containerization of the applications makes sense, it should be used.

System administrators should be able to directly manage each of these three "containers" from the same pane of glass, and as part of my demo, I'll be showing just that using XenCenter. XenCenter has a simple GUI from which host and VM level management can be performed, and which is in the process of being extended to include Dockerized containers.

With this as the demo backdrop, I encourage anyone planning on attending FOSDEM to please stop by and ask about the work we've done with Creedence and also where we're thinking of going. If you're a contributor to a project and would like to talk more about how integrating with XenServer might make sense, either for your project or as something we should be thinking about, please do feel free to reach out to me. Of course if you're not planning on being at FOSDEM, but know folks who are, please do feel free to have them seek me out. We want XenServer to be a serious contender in every data center, but if we don't know about issues facing your favorite projects, we can't readily work to resolve them.

btw, if you'd like to plan anything around FOSDEM, please either comment on this blog, or contact me on Twitter as @XenServerArmy.

-tim     

Recent Comments
Tobias Kreidl
Thank you for sharing this, Tim. Some progress has already been made in being able to export VHD files and even VHD snapshots, so ... Read More
Monday, 26 January 2015 20:39
Felipe Franciosi
For those arriving in Brussels a day earlier, I'll be presenting at the CentOS Dojo and talking about Optimising Xen Deployments f... Read More
Tuesday, 27 January 2015 09:07
Tobias Kreidl
Tim, Would like to see a summary of your experiences and impressions at FOSDEM after it has concluded.
Sunday, 01 February 2015 15:54
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XenServer Support Options

Now that Creedence has been released as XenServer 6.5, I'd like to take this opportunity to highlight where to obtain what level of support for your installation.

Commercial Support

Commercial support is available from Citrix and many of its partners. A commercial support contract is appropriate if you're running XenServer in a production environment, particularly if downtime is a critical component of your SLA. It's important to note that commercial support is only available if the deployment follows the Citrix deployment guidelines, uses third party components from the Citrix Ready Marketplace, and is operated in accordance with the terms of the commercial EULA. Of course, since your deployment might not precisely follow these guidelines, commercial support may not be able to resolve all issues and that's where community support comes in.

Community Support

Community support is available from the Citrix support forums. The people on the forum are both Citrix support engineers and also your fellow system administrators. They are generally quite knowledgeable and enthusiastic to help someone be successful with XenServer. It's important to note that while the product and engineering teams may monitor the support forums from time to time, engineering level support should not be expected on the community forums.

Developer Support

Developer level support is available from the xs-devel list. This is your traditional development mailing list and really isn't appropriate for general support questions. Many of the key engineers are part of this list, and do engage on topics related to performance, feature development and code level issues. It's important to remember that the XenServer software is actually built from many upstream components, so the best source of information might be an upstream developer list and not xs-devel.

Self-support tool

Citrix maintains an self-support tool called Citrix Insight Services, formerly known as Tools-as-a-Service (TaaS). Insight Services takes a XenServer status report, and analyzes it to determine if there are any operational issues present in the deployment. A best practice is to upload a report after installing a XenServer host to determine if any issues are present which can result in latent performance or stability problems. CIS is used extensively by the Citrix support teams, but doesn't require a commercial support contract for end users.

Submitting Defects

If you believe you have encountered a defect or limitation in the XenServer software, simply using one of these support options isn't sufficient for the incident to be added to the defect queue for evaluation. Commercial support users will need to have their case triaged and potentially escalated, with the result potentially being a hotfix. All other users will need to submit an incident report via bugs.xenserver.org. Please be as detailed as possible with any defect reports such that they can be reproduced, and it doesn't hurt to include the URL of any forum discussion or the TaaS ID in your report. Also, please be aware that while the issue may be urgent for you any potential fix may take some time to be created. If your issue is urgent, you are strongly encouraged to follow the commercial support route as Citrix escalation engineers have the ability to prioritize customer issues.

Additionally, its important to point out that submitting a defect or incident report doesn't guarantee it'll be fixed. Some things simply work the way they do for very important reasons, other things may behave the way they do due to the way components interact. XenServer is tuned to provide a highly scalable virtualization platform, and if an incident would require destabilizing that platform, it's unlikely to be changed.

Recent comment in this post
JK Benedict
Tim - thank you very much for this post and as always, we greatly appreciate your work here @ xenserver.org. #XenServer = #Citr... Read More
Friday, 16 January 2015 04:37
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Creedence launches as XenServer 6.5

Today the entire XenServer team is very proud to announce that Creedence has officially been released as XenServer 6.5. It is available for download from xenserver.org, and is recommended for all new XenServer installs. We're so confident in what has been produced that I'm encouraging all XenServer 6.2 users to upgrade at their earliest convenience. So what have we actually accomplished?

The headline features

Every product release I've ever done, and there have been quite a large number over the years, has had some headline features; but Creedence is a bit different. Creedence wasn't about new features, and Creedence wasn't about chasing some perceived competitor. Creedence very much was about getting the details right for XenServer. It was about creating a very solid platform upon which anyone can comfortably, and successfully, build a virtualized data center regardless of workload. Creedence consisted of a lot of mundane improvements whose combination made for one seriously incredible outcome; Creedence restored the credibility of XenServer within the entire virtualization community. We even made up some t-shirts that the cool kids want ;)

So let's look at some of those mundane improvements, and see just how significant they really are.

  • 64 bit dom0 freed us from the limitations of dreaded Linux low memory, but also allows us to use modern drivers and work better with modern servers. From personal experience, when I took alpha.2 and installed it on some of my test Dell servers, it automatically detected my hardware RAID without my having to jump through any driver disk hoops. That was huge for me.
  • The move to a 3.10 kernel from kernel.org meant that we were out of the business of having a completely custom kernel and corresponding patch queue. Upstream is goodness.
  • The move to the Xen Project hypervisor 4.4 meant that we're now consuming the most stable version of the core hypervisor available to us.
  • We've updated to an ovs 2.10 virtual switch giving us improved network stability when the virtual switch is under serious pressure. While we introduced the ovs way back in December of 2010, there remained cases where the legacy Linux bridge worked best. With Creedence, those situations should be very few and far between
  • A thread per vif model was introduced to better ensure network hogs didn't impact adjacent VM performance
  • Network datapath optimizations allow us to drive line rate for 10Gbps NICs, and we're doing pretty well with 40Gbps NICs.
  • Storage was improved through an update to tapdisk3, and the team did a fantastic job of engaging with the community to provide performance details. Overall we've seen very significant improvements in aggregate disk throughput, and when you're virtualizing it's the aggregate which matters more than the single VM case.

What this really means for you is that XenServer 6.5 has a ton more headroom than 6.2 ever did. If you happen to be on even older versions, you'll likely find that while 6.5 looks familiar, it's not quite like any other XenServer you've seen. As has been said multiple times in blog comments, and by multiple people, this is going to be the best release ever. In his blog, Steve Wilson has a few performance graphs to share for those doubters. 

The future

While today we've officially released Creedence, much more work remains. There is a backlog of items we really want to accomplish, and you've already provided a pretty long list of features for us to figure out how to make. The next project will be unveiled very soon, and you can count on having access to it early and being able to provide feedback just as the thousands of pre-release participants did for Creedence. Creedence is very much a success of the community as it is an engineering success.

Thank you to everyone involved. The hard work doesn't go unnoticed.     

Recent Comments
Fabian
Finally! Now hope that it's as stable in production as it was during the testing phase... Fingers crossed here. BTW: There's a ty... Read More
Tuesday, 13 January 2015 19:32
Tim Mackey
@James, thanks for the kinds words @Fabian, I would expect things to be just as stable, and thanks for the catch.... Read More
Tuesday, 13 January 2015 19:39
Tobias Kreidl
Did DVSC ever get bundled in with the free or at least other versions?
Tuesday, 13 January 2015 19:42
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Understanding why certain Creedence builds don't work with certain features

Over the year end break, there were a couple of posts to the list which asked a very important question: "Does the DVSC work with the Release Candidate?" The answer was a resounding "maybe", and this post is intended to help clarify some of the distinction between what you get from xenserver.org, what you get from citrix.com, and how everything is related.

At this point most of us are already familiar with XenServer virtualization being "open source", and that with XenServer 6.2 there was no functional difference between the binary you could download from citrix.com and that from xenserver.org. Logically, when we started the Creedence pre-release program, many assumed that the same download would exist in both locations, and that everything which might be part of a "XenServer" would also always be open source. That would be really cool for many people, and potentially problematic for others.

The astute follower of XenServer technology might also have noticed that several things commonly associated with the XenServer product never had their source released. StorageLink is a perfect example of this. Others will have noticed that the XenServer Tech Preview run on citrix.com included a number of items which weren't present in any of the xenserver.org pre-release builds, and for which the sources aren't listed on xenserver.org. There is of course an easy explanation for this, but it goes to the heart of what we're trying to do with xenserver.org.

xenserver.org is first and foremost about the XenServer platform. Everyone associated with xenserver.org, and by extension the entire team, would love for the data centers of the world to standardize on this platform. The core platform deliverable is called main.iso, and that's the thing from which you install a XenServer host. The source for main.iso is readily available, and other than EULA differences, the XenServer host will look and behave identically regardless of whether main.iso came from xenserver.org or citrix.com. The beauty of this model is that when you grow your XenServer based data center to the point where commercial support makes sense, the software platform you'd want supported is the same.

All of which gets me back to the DVSC (and other similar components). DVSC, StorageLink and certain other "features" include source code which Citrix has access to under license. Citrix provides early access to these feature components to those with a commercial relationship. Because there is no concept of a commercial relationship with xenserver.org, we can't provide early access to anything which isn't part of the core platform. Now of course we do very much want everyone to obtain the same XenServer software from both locations, so when an official release occurs, we mirror it for your convenience.

I hope this longish explanation helps clarify why when questions arise about "features" not present in main.iso that the response isn't as detailed as some might like. It should also help explain why components obtained from prior "Tech Preview" releases might not work with newer platform builds obtained as part of a public pre-release program.

Recent Comments
Tim Mackey
@xiao, It went live this morning, and you can download it from xenserver.org
Tuesday, 13 January 2015 19:40
Tim Mackey
@Nick I think a better way of thinking about this is that the hypervisor is free, and the platform features and functions are fre... Read More
Tuesday, 27 January 2015 23:43
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Trading for Creedence shirts

Update: The t-shirt promotion has closed.

While there are still a couple of stops left on the Creedence world tour, we recognize it's impossible for us to cover all of our enthusiastic followers. That being said, we do want to give everyone an opportunity to cover themselves with one of our lovely Creedence World Tour t-shirts. Quite honestly, I've been rather impressed with how popular these have proven to be, and there is no good reason not to provide them to the community at large.

b2ap3_thumbnail_creedence_support.png

So this is where I offer these lovely shirts to you guys, and hope for something small in return. I'm in the process of revamping xenserver.org and want to add in some quotes about either of XenServer or Creedence. In return for your quote, I'm willing to trade some Creedence shirts. Now of course, I do understand that you might not be in a position to speak on behalf of your employer, so before anything gets posted I'll contact you to verify what can be said; and how you'd be attributed.    

If you're interested, all you need to do is fill out this small survey on Creedence, and select the option to provide a quote. The survey is very short, but the quote you might provide could go a long way to helping others believe in the effort we've put into Creedence, and that XenServer is a compelling platform for them to look at.  Of course, do feel free to forward this to those who might not be following this blog ;)

Recent Comments
JK Benedict
Ha! I see Blaine's photo of Dave and myself didn't make the cut ... Read More
Tuesday, 06 January 2015 19:52
Tim Mackey
He sent me three, but I didn't see you in any!
Tuesday, 06 January 2015 19:55
JK Benedict
Hehehe - it is quite alright, sir! I think this is great and I appreciate everything. I had noticed the Alpharetta team while ti... Read More
Tuesday, 06 January 2015 20:45
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Creedence Release Candidate Available

Just in time for the holiday season - we're pleased to announce a another tech toy for the geeks of the world to play with. Now of course XenServer is serious business, but just like many kids toys, the arrival of Creedence is eagerly awaited by many. As I mentioned earlier this week, you'll have to wait a bit longer for the official release, but today you can download the release candidate and see exactly what the world of Creedence should look like. Andy also mentioned last week that we're closing out the alpha/beta program, and as part of that effort the nightly Creedence snapshot page has been removed. You can still access the final beta (beta.3) on the pre-release page, but all prior builds have been removed. The pre-release page is also where you can download the release candidate.

What's in the Release Candidate

Performance tuning

The release candidate contains a number of bug fixes, but also has had some performance tuning done on it. This performance tuning is a little bit different than what we normally talk about, so if you've been benchmarking Creedence, you'll want to double check with the release candidate. What we've done is take a look at the interaction of a variety of system components and put in some limits on how hard we'll let you push them. Our first objective is a rock solid system, and while this work doesn't result in any configuration limit changes (at least not yet - that comes later in our cycle), it could reduce some of the headroom you might have experienced with a prior build. It's also possible that you could experience better headroom due to an overall improvement in system stability, so doing a performance test or two isn't a bad idea.

Core bug fixes over beta.3

  • mulitpath.conf is now preserved as multipath.conf.bak on upgrade
  • The default cpufreq governor is now set to performance
  • Fixes for XSA-109 through XSA-114 inclusive
  • Increase the number of PIRQs to more than 256 to support large quantities of NICs per host

What we'd like you to do with this build

The core two things we'd like you to do with this build are:

  1. If you've reported any issue at https://bugs.xenserver.org, please validate that we did indeed get the issue addressed.
  2. If you can, run this release candidate through its paces. We think it's nice and solid, and hope you do too.

Lastly, I'd like to take this opportunity to wish everyone in our community a festive end to 2014 and hope that what ever celebrating you might do is enjoyable. 2014 was an exciting year for XenServer, and that's in large part to the contributions of everyone reading this blog and working with Creedence. Thank you.

 

-tim     

Recent Comments
Tassos Papadopoulos
Boot from iSCSI is not supported on XS6.2. We had to do some hacks to do make it possible on Cisco UCS Blades. Are you going to su... Read More
Monday, 22 December 2014 07:21
Itaru OGAWA
Is "xe vm-export" performance improved in Creedence? From my test on RC, it looks similar, around 15MB/sec, even on 10GBE link: ... Read More
Monday, 22 December 2014 17:03
Tim Mackey
@Nathan, Since this is pre-release software intended for testing, no official upgrade path exists to the final release. Practica... Read More
Monday, 05 January 2015 19:53
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About XenServer

XenServer is the leading open source virtualization platform, powered by the Xen Project hypervisor and the XAPI toolstack. It is used in the world's largest clouds and enterprises.
 
Commercial support for XenServer is available from Citrix.