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Having several virtual servers with Windows 2008 R2 at our web hoster (Germany's "1&1", they seem to use Citrix Xen), I have every now and then some servers that hang (RDP login screen hangs forever).

Only turning the server off and on again via the hoster's web control panel helps "resolving" this.

After this reboot, I find an entry in the event log:

Log name: System
Source: xennet6
Event ID: 5001

The description for Event ID 5001 from source xennet6 cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

\Device\NDMP1 Citrix PV Ethernet Adapter #0

When looking in the "Uninstall Programs" in Windows I see an entry

"Citrix Tools for Virtual machines".

From pure guessing, I could imagine that this tool may be a cause for the issue.

So I searched Google and Citrix Xen forums to see and information for what this tool is intended and whether it would be safe to remove it.

Unfortunately I found no answer. What I found is this long thread on the Citrix forums, which I do not understand fully.

Therefore my question is:

Is it safe to uninstall "Citrix Tools for Virtual machines" from my Windows 2008 R2 64-Bit Server?

("Save" in terms of "The server still boots and runs normally")

Update 2013-04-23:

Following the fantastic answer of syneticon-dj, I contacted the 1&1 support, asking about how to fix the server halts. They first suggested to:

  • Disable IPv6.
  • Delete all not-required network adapters.

Since I already did both without success, I pointed them to this Server Fault posting, asking whether it is safe to upgrade Xen Tools as pointed out in the Rackspace KB article.

They answered something vague like:

"Give it a try, from our point-of-view, nothing should go wrong. If it real helps you have to see afterwards".

So I now have one server updated five days ago with no more errors since then; I updated another server today, no errors there, too.

(I did a snapshot of the server through the 1&1 web UI console before upgrading the tools)

In addition, just to tell you, I've also uninstalled Cobian Backup which I really don't trust that much. I now dow my backups without the Volume Shadow Copy service with a simple script and WinSCP.

Update 2013-05-31:

Just as a future reference on how to get the Citrix Tools for Windows:

  1. Go to the download page on the Citrix server or use this direct download page. (version 6.1 as of writing)
  2. Find "XenServer-6.1-install-cd.iso" (If you don't find it, here is a direct link that hopefully does not expire).
  3. Extract the ISO to a folder (e.g. simply double-click the ISO file on Windows 8 or use Iso Buster)
  4. Find the folder "client_install"
  5. Copy the content to your Windows 2008 Server.
  6. Execute "windows-pvdrivers-xenlegacy.exe" by double-clicking.

It also seems that the previously disabled IPv6 got re-enabled by the installation process. So be sure to remove the "Internet Protocol Version 6 (TCP/IPv6)" check box again in the properties of the Citrix PV Ethernet Adapter #0.

Update 2013-06-14:

A newer version for the Citrix Xen Tools for Windows is available here (alternative download). This is an extract from the Hotfix XS61E010.

Update 2013-08-08:

There is a new version 6.2 available on this download page.

Update 2013-10-28:

We solved the issues by moving the server(s) away from the Xen hosting provider to another provider that has real hardware machines. (Google-translated blog article about the details for those interested)

Update 2014-05-13:

This is the link to the downloads of the Xen Tools that my hosting provider officially told me by email.

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1 Answer 1

up vote 7 down vote accepted

Short answer: no, it is not. From a recent RackSpace KB article possibly outlining the root cause of your problem:

Uninstalling the existing XenServer Tools software will render your server inaccessible.

This is due to the simple fact that the XenServer tools contain paravirtualized drivers (networking, storage) necessary for the virtual system to function correctly. Also:

An earlier version of the XenServer Tools software [...] has been found to cause server instability in rare cases. [...]

If the listed version is less than 6.0-58937 you should upgrade.

share|improve this answer
    
Thank you! My version is "6.0.50762". –  Uwe Keim Apr 17 '13 at 10:02
    
Is there some official download for the Tools or could I use the RackSpace one? –  Uwe Keim Apr 17 '13 at 10:10
2  
@UweKeim the proper way would involve asking 1&1 support for an updated version. You could refer them to the thread in the Citrix forums you've linked and to the Rackspace KB article and indicate that you suspect that your machines might be affected by a bug resolved in a more recent XenServer tools release. If this is not feasible, download the current XenServer release ISO from the Citrix downloads, extract the tools from the ISO and check if the newer version resolves your problem. –  the-wabbit Apr 17 '13 at 11:09
2  
@UweKeim important: installing a newer version of XenServer tools all on your own likely puts your servers into a state which would be considered "unsupported" by 1&1. Make sure you have a backup or a snapshot to revert to, should things go bad. –  the-wabbit Apr 17 '13 at 11:11
    
Thanks a lot! I'll take a snapshot before proceeding. And I'll mark your answer as "accepted", because I do think it is phantastic! –  Uwe Keim Apr 17 '13 at 12:15

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