Virtualization Blog

Discussions and observations on virtualization.

XenCenter 7.1 update now available!

A hotfix (XS71E001) has been released for customers using XenCenter as the management console for their XenServer 7.1 virtual environments. 

This hotfix offers improvements in XenCenter UI responsiveness, as well as several fixes associated with host health check analysis, status reports and updates. Additional information pertaining to this hotfix can be found here.

As always, we encourage customers read the hotfix release notes and install the hotfix to avoid any of the issues described in the notes.

 

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Better Together: PVS and XenServer!

XenServer adds new functionality to further simplify and enhance the secure and on-demand delivery of applications and desktops to enterprise environments.

If you haven't visited the Citrix blogs recently, we encourage you to visit https://www.citrix.com/blogs/2016/10/31/pvs-and-xenserver-better-together/ to read about the latest integration efforts between PVS and XS.

If you're a Citrix customer, this article is a must read!

Andy Melmed, Senior Solutions Architect, XenServer PM

 

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XenServer Hotfix XS65ESP1035 Released

XenServer Hotfix XS65ESP1035 Released

News Flash: XenServer Hotfix XS65ESP1035 Released

Indeed, I was alerted early this morning (06:00 EST) via email that Citrix has released hotfix XS65ESP1035 for XenServer 6.5 SP1.  The official release and content is filed under CTX216249, which can be found here: http://support.citrix.com/article/CTX216249

As of the writing of this article, this hotfix has not yet been added to CTX138115 (entitled "Recommended Updates for XenServer Hotfixes") or, as we like to call it "The Fastest Way to Patch A Vanilla XenServer With One or Two Reboots!"  I imagine that resource will be updated to reflect XS65ESP1035 soon.

Personally/Professionally, I will be installing this hotfix as, per CTX216249, I am excited to read what is addressed/fixed:

  • Duplicate entry for XS65ESP1021 was created when both XS65ESP1021 and XS65ESP1029 were applied.
  • When BATMAP (Block Allocation Map) in Xapi database contains erroneous data, the parent VHD (Virtual Hard Disk) does not get inflated causing coalesce failures and ENOSPC errors.
  • After deleting a snapshot on a pool member that is not the pool master, a coalesce operation may not succeed. In such cases, the coalesce process can constantly retry to complete the operation, resulting in the creation of multiple RefCounts that can consume a lot of space on the pool member.
In addition, this hotfix contains the following improvement:
  • This fix lets users set a custom retrans value for their NFS SRs thereby giving them more fine-grained control over how they want NFS mounts to behave in their environment.

(Source: http://support.citrix.com/article/CTX216249)

So....

This is storage based hotfix and while we can create VMs all day, we rely on the storage substrate to hold our precious VHDs, so plan accordingly to deploy it!

Applying The Patch Manually

As a disclaimer of sorts, always plan your patching during a maintenance window to prevent any production outages.  For me, I am currently up-to-date and will be rebooting my XenServer host(s) in a few hours, so I manually applied this patch.

Why?  If you look in XenCenter for updates, you won't see this hotfix listed (yet).  If it was available in XenCenter, checks and balances would inform me I need to suspend, migrate, or shutdown VMs.  For a standalone host, I really can't do that.  In my pool, I can't reboot for a few hours, but I need this patch installed, so I simply do the following on my XenServer stand-alone server OR XenServer primary/master server:

Using the command line in XenCenter, I make a directory in /root/ called "ups" and then descend into that directory because I plan to use wget (Web Get) to download the patch via its link in http://support.citrix.com/article/CTX216249:

[root@colossus ~]# mkdir ups
[root@colossus ~]# cd ups

Now, using wget I specify what to download over port 80 and to save it as "hf35.zip":

[root@colossus ups]# wget http://support.citrix.com/supportkc/filedownload?uri=/filedownload/CTX216249/XS65ESP1035.zip -O hf35.zip

We then see the usual wget progress bar and once it is complete, I can unzip the file "hf35.zip":

HTTP request sent, awaiting response... 200 OK
Length: 110966324 (106M) [application/zip]
Saving to: `hf35.zip'

100%[======================================>] 110,966,324 1.89M/s   in 56s    
2016-08-25 11:06:32 (1.90 MB/s) - `hf35.zip' saved [110966324/110966324]
[root@colossus ups]# unzip hf35.zip 
Archive:  hf35.zip
  inflating: XS65ESP1035.xsupdate   
  inflating: XS65ESP1035-src-pkgs.tar.bz2

I'm a big fan of using shortcuts - especially where UUIDs are involved.  Now that I have the patch ready to expand onto my XenServer master/stand-alone server, I want to create some kind of variable so I don't have to remember my host's UUID or the patch's UUID. 

For the host, I can simply source in a file that contains the XenServer primary/master server's INSTALLATION_UUID (better known as the host's UUID):

[root@colossus ups]# source /etc/xensource-inventory 
[root@colossus ups]# echo $INSTALLATION_UUID
207cd7c1-da20-479b-98bc-e84cac64d0c0

With the variable $INSTALLATION_UUID set, I can now expand the patch and capture it's own UUID:

[root@colossus ups]# patchUUID=`xe patch-upload file-name=XS65ESP1035.xsupdate`
[root@colossus ups]# echo $patchUUID
cdf9eb54-c3da-423d-88ca-841b864f926b

NOW, I apply the patch to the host (yes, it still needs to be rebooted, but within a few hours) using both variables in the following command:

[root@colossus ups]# xe patch-apply uuid=$patchUUID host-uuid=$INSTALLATION_UUID
   
Preparing...                ##################################################
kernel                      ##################################################
unable to stat /sys/class/block//var/swap/swap.001: No such file or directory
Preparing...                ##################################################
sm                          ##################################################
Preparing...                ##################################################
blktap                      ##################################################
Preparing...                ##################################################
kpartx                      ##################################################
Preparing...                ##################################################
device-mapper-multipath-libs##################################################
Preparing...                ##################################################
device-mapper-multipath     ##################################################

At this point, I can back out of the "ups" directory and remove it.  Likewise, I can also check to see if the patch UUID is listed in the XAPI database:

[root@colossus ups]# cd ..
[root@colossus ~]# rm -rf ups/
[root@colossus ~]# ls
support.tar.bz2
[root@colossus ~]# xe patch-list uuid=$patchUUID
uuid ( RO)                    : cdf9eb54-c3da-423d-88ca-841b864f926b
              name-label ( RO): XS65ESP1035
        name-description ( RO): Public Availability: fixes to Storage
                    size ( RO): 21958176
                   hosts (SRO): 207cd7c1-da20-479b-98bc-e84cac64d0c0
    after-apply-guidance (SRO): restartHost

So, nothing really special -- just a quick way to apply patches to a XenServer primary/master server.  In the same manner, you can substitute the $INSTALLATION_UUID with other host UUIDs in a pool configuration, etc.

Well, off to reboot and thanks for reading!

 

-jkbs | @xenfomationMy Citrix Blog

To receive updates about the latest XenServer Software Releases, login or sign-up to pick and choose the content you need from http://support.citrix.com/customerservice/

 


Sources

Citrix Support Knowledge Center: http://support.citrix.com/article/CTX216249

Citrix Support Knowledge Center: http://support.citrix.com/customerservice/

Citrix Profile/RSS Feeds: http://support.citrix.com/profile/watches/

Original Image Source: http://www.gimphoto.com/p/download-win-zip.html

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Resetting Lost Root Password in XenServer 7.0

XenServer 7.0, Grub2, and a Lost Root Password

In a previous article I detailed how one could reset a lost root password to XenServer 6.2.  While the article is not limited to 6.2 (it works just as well for 6.5, 6.1, and 6.0.2), this article is dedicated to XenServer 7.0 as grub2 has been brought in to replace extlinux.

As such, if the local root user's (LRU) password for a XenServer 7.0 is forgotten physical (or "lights out") access to the host and a reboot will be required.  The contrast comes with grub2, the methods to boot the XenServer 7.0 host into single user mode, and how to reset the root password to a known token.

The Grub Boot Screen

Once obtaining physical or "lights out" to the XenServer 7.0 host in question, on reboot the following screen will appear:

It is important to note that once this screen appears, you only have four seconds to take action before the host proceeds to boot the kernel.

As should be default, the XenServer kernel is highlighted.  One will want to immediately press the key (for edit).

This will then refresh the grub interface - stopping any count-down-to-boot timers - which will reveal the boot entry.  It is within this window (using up, down, left, and right) one will want to navigate to around line 4 or five and isolate "ro nolvm":

 

Next, one will want to remove (or backspace/delete) the "ro" characters and type in "rw init=/sysroot/bin/sh", or as illustrated:

 

Don't worry if the directive is not on one line!

 

With this change made, press both Control and X at the same time as this will boot the XenServer kernel into single user style mode, or better known as Emergency Mode:

How to Change Root's Password

From the Emergency Mode prompt, execute the following command:

chroot /sysroot

Now, once can execute the "passwd" command to change root's credentials:

Finally....

Now that root's credentials have been changed, utilize Control+Alt+Delete to reboot the XenServer 7.0 host and one will find via SSH, XenCenter, or directly that the root password has been changed: the host is ready to be managed again.

 

Recent Comments
Tobias Kreidl
Many thanks for this update, Jesse! It should be turned into a KB article, as well, if not already.
Friday, 24 June 2016 10:52
JK Benedict
Jordan -- Thanks for the compliments! However, it seems more apropos to say "Sorry to hear about your situation!" So, the steps... Read More
Monday, 27 June 2016 10:11
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XenServer Pre-Release Programme

A very big thank you for everyone who participated in the Creedence Alpha/Beta programme! 
The programme was very successful and raised a total of 177 issues, of which 138 were resolved during the Alpha/Beta period.  We are reviewing how the pre-release process can be improved and streamlined going forward. 

The Creedence Alpha/Beta programme has now come to an end with the focus of nightly snapshots moving on to the next version of XenServer.   

The Creedence Alpha/Beta source code remains available and can be accessed here: 
http://xenserver.org/component/content/article/24-product/creedence/143-xs-2014-development-snapshots.html

Creedence Alpha/Beta bugs may still be reported on https://bugs.xenserver.org

Work is already progressing on the next version of XenServer and the nightly snapshots are available here:
http://xenserver.org/component/content/article/2-uncategorised/115-development-snapshots.html

As this work is new and still expected to be unstable, please do not raise any Creedence Alpha/Beta bugs against it.

Recent Comments
Andrew Halley
Hi there, we are working towards posting an updated build containing all the bug fixes received to date, and which is fully integr... Read More
Sunday, 14 December 2014 12:33
Tobias Kreidl
Andrew, Thanks go to you and the whole Citrix team for making this a really great overall experience. Each XenServer release seems... Read More
Wednesday, 10 December 2014 19:45
Andrew Halley
Appreciate it Tobias - and our thanks to all the excellent contributions received from our community.
Sunday, 14 December 2014 12:33
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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.