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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).     

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Comments 11

Tobias Kreidl on Wednesday, 16 March 2016 03:08

Given the importance of thin provisioning for block-based storage devices, I'm sure that Citrix will find a solution. It takes making a hard decision sometimes to make the right one and it is praiseworthy to defer something like this in the interest of stability and reliability. Thank you for the continued efforts spent improving XenServer and its feature sets.

0
Given the importance of thin provisioning for block-based storage devices, I'm sure that Citrix will find a solution. It takes making a hard decision sometimes to make the right one and it is praiseworthy to defer something like this in the interest of stability and reliability. Thank you for the continued efforts spent improving XenServer and its feature sets.
Tim Mackey on Wednesday, 16 March 2016 13:32

@Tobias

Thanks. We haven't given up on thin provisioned block at all. We're already down a different path which is looking promising!

-tim

0
@Tobias Thanks. We haven't given up on thin provisioned block at all. We're already down a different path which is looking promising! -tim
Guest - Davide Bozzelli on Wednesday, 16 March 2016 16:58

Hi Tim

Is it possible to know something about this "different path" ?
Giving up lvm thin provision which is mainly derived from original kernel code would not be a simple choice ... so you should have choose a radical new way .

0
Hi Tim Is it possible to know something about this "different path" ? Giving up lvm thin provision which is mainly derived from original kernel code would not be a simple choice ... so you should have choose a radical new way .
Gianni D on Wednesday, 16 March 2016 04:26

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 even show. Option is available for vms running on Beta 3 hosts. Downgrading to old XenCenter restores functionality but doesn't allow managment of upgraded hosts, as expected.

0
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 even show. Option is available for vms running on Beta 3 hosts. Downgrading to old XenCenter restores functionality but doesn't allow managment of upgraded hosts, as expected.
Tim Mackey on Wednesday, 16 March 2016 13:29

@Gianni

I can't think of why that might be. If you've not yet done so, please report this on https://bugs.xenserver.org.

-tim

0
@Gianni I can't think of why that might be. If you've not yet done so, please report this on https://bugs.xenserver.org. -tim
Willem Boterenbrood on Wednesday, 16 March 2016 12:00

Hello Tim,

While I am happy there is some news about progress in Dundee after months of silence I must admit the contents of your post taste a little sour. Not only is one of the more popular requested features now absent from this release, a feature that both VMware and HyperV have for some time now. Also your mention of feature complete means that there is no Changed Block Tracking, another popular requested feature that again both VMware and HyperV have and really helps by significantly reducing backup time. And a lack of any built-in support for a distributed storage system like Ceph, GlusterFS and even Citrix own Melio leaves me wondering how much progress has been made from a user perspective.

Support for CPU leveling of the newer Intel CPU's is very welcome and much needed as the lack-there-of from a user perspective was reduced functionality so it does not count as a new feature in my opinion while it did take many hours of development time.

I am very interested in the future plans for XenServer and I do hope the new open source model will add many more programmers to the team over time. Dundee does feature many improvements that cost a lot of time and not impact the users in a very direct sense, like Centos 7.2 support. These changes give us hope for the future and I really hope Dundee will see some of the above named new features appear on the roadmap for the not to distant future.

I wish you and team all the best and hope to hear about the future directions soon.

0
Hello Tim, While I am happy there is some news about progress in Dundee after months of silence I must admit the contents of your post taste a little sour. Not only is one of the more popular requested features now absent from this release, a feature that both VMware and HyperV have for some time now. Also your mention of feature complete means that there is no Changed Block Tracking, another popular requested feature that again both VMware and HyperV have and really helps by significantly reducing backup time. And a lack of any built-in support for a distributed storage system like Ceph, GlusterFS and even Citrix own Melio leaves me wondering how much progress has been made from a user perspective. Support for CPU leveling of the newer Intel CPU's is very welcome and much needed as the lack-there-of from a user perspective was reduced functionality so it does not count as a new feature in my opinion while it did take many hours of development time. I am very interested in the future plans for XenServer and I do hope the new open source model will add many more programmers to the team over time. Dundee does feature many improvements that cost a lot of time and not impact the users in a very direct sense, like Centos 7.2 support. These changes give us hope for the future and I really hope Dundee will see some of the above named new features appear on the roadmap for the not to distant future. I wish you and team all the best and hope to hear about the future directions soon.
Tim Mackey on Wednesday, 16 March 2016 13:34

@Willem

I continue to evangelize internally for distributed storage support. At this point, I'm reasonably certain many of them expect any conversation to include the Ceph word!

-tim

0
@Willem I continue to evangelize internally for distributed storage support. At this point, I'm reasonably certain many of them expect any conversation to include the Ceph word! -tim
Guest - Davide Bozzelli on Wednesday, 16 March 2016 16:54

BTW consider gluster too.... with it you could achieve a good hyperconverge
solution at dom0 level with thin provision inherited from file level sr...

0
BTW consider gluster too.... with it you could achieve a good hyperconverge solution at dom0 level with thin provision inherited from file level sr...
Tobias Kreidl on Wednesday, 16 March 2016 21:07

GlusterFS as a standalone storage device will allow volumes, such as via NFS, to be picked up by XenServer. Recent experiments I've read on the Citrix discussion forum still point to some stability and performance issues. Honestly, I'm not sure why I'd want or care if it were available as local storage. Distributed file systems should be -- well -- distributed. As to Ceph, there were performance issues when there was a beta trial of this a couple of years ago. A generic plugin for external storage, while fairly easy to do and useful, doesn't mesh well with the well-established utilities for VDI manipulation, and this is where things are more complex because of the need to either preserve these aspects or to be willing to go down a whole different, parallel path. Support and resources are always factors that need to be considered.

Storage performance is a key factor as the size of servers continues to rise and I find it encouraging to see Citrix engaged in working on all aspects of performance improvements while also striving to add features. Resources are going to constrain what areas can be given the most immediate attention. Looking at what all has changed over the last two years in particular has been encouraging.

0
GlusterFS as a standalone storage device will allow volumes, such as via NFS, to be picked up by XenServer. Recent experiments I've read on the Citrix discussion forum still point to some stability and performance issues. Honestly, I'm not sure why I'd want or care if it were available as local storage. Distributed file systems should be -- well -- [i]distributed[/i]. As to Ceph, there were performance issues when there was a beta trial of this a couple of years ago. A generic plugin for external storage, while fairly easy to do and useful, doesn't mesh well with the well-established utilities for VDI manipulation, and this is where things are more complex because of the need to either preserve these aspects or to be willing to go down a whole different, parallel path. Support and resources are always factors that need to be considered. Storage performance is a key factor as the size of servers continues to rise and I find it encouraging to see Citrix engaged in working on all aspects of performance improvements while also striving to add features. Resources are going to constrain what areas can be given the most immediate attention. Looking at what all has changed over the last two years in particular has been encouraging.
Guest - Marc on Sunday, 20 March 2016 03:32

Excellent! Is there a timescale from BETA.3 to Final Release yet?

We're currently experiencing an issue with a new Haswell-EP Xeon processors on one box (our fault for ordering a new server *cries*) being masked to our older maskable Sandy Bridge box. Oops!

I don't want to test in a production environment, but a timescale would help us assess if we should change out the newer CPU's temporarily or just wait?

0
Excellent! Is there a timescale from BETA.3 to Final Release yet? We're currently experiencing an issue with a new Haswell-EP Xeon processors on one box (our fault for ordering a new server *cries*) being masked to our older maskable Sandy Bridge box. Oops! I don't want to test in a production environment, but a timescale would help us assess if we should change out the newer CPU's temporarily or just wait?
Tobias Kreidl on Sunday, 20 March 2016 16:20

@Marc: Citrix never publishes or announces release dates ahead of time for legal reasons. If I were to bet, I'd say a release in conjunction with Synergy 2016 in May would be a good possibility.

0
@Marc: Citrix never publishes or announces release dates ahead of time for legal reasons. If I were to bet, I'd say a release in conjunction with Synergy 2016 in May would be a good possibility.

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.
 
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