Citrix Xen Servers Slow to Start, Not Reporting Memory in Xen Center

Hello Experts,

I am running two XenServers at version 6.0.

Recently did an upgrade to my backend SAN and am noticing XenServer issues now.

When I go to launch a VM - the "Starting" task now lingers for a really long time, even after the VM has started. Sometimes it will take several minutes for the VM to even begin the process of  booting up. This used to be really fast. Server performance also seems degraded.

In addition, the memory utilization for all VMs running on my second xenserver isn't reporting on XenCenter when I view the pool or the second xenserver. When I move the VM over to my primary xenserver, memory reports. Move it back again, no memory listed on the pool screen.

Any ideas on what might be going on? I have had HP check on the SAN and have another ticket open to explore one possible issue there, however at this point they feel that everything is good there.

Thanks.
epaschalAsked:
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Scott GorcesterCTOCommented:
did you upgrade the xentools in the vm's?  Is this an iSCSI san?
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Ayman BakrSenior ConsultantCommented:
First on how many paths are your XenServers connected to the new SAN? Citrix supports a max of 8 paths.
If you are OK at 8 paths then check your XenServers and VMs for disabling TaskOffloading; the following article should help: http://www.xenappblog.com/2010/citrix-xenserver-slow-network-performance/
Hope this helps.
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epaschalAuthor Commented:
I should clarify I just did a firmware update to the San, nothing but the enclosure firmware was updated. All servers have latest version of xentools. As for the San I'm pretty green there, it's not fibre it's just connected with Ethernet cables.
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Ayman BakrSenior ConsultantCommented:
In any case, it would be better if you disabled TaskOffloading on both groups: your VMs and XenServers. Give it a try let's say on one XenServer and one VM started on that XenServer and see what happens.
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Ayman BakrSenior ConsultantCommented:
Just to make things clear, the script in the article would disable taskoffloading on all your XenServers. If you want to test with one XenServer only then you need to either modify the script or run the commands manually on that XenServer.
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Ayman BakrSenior ConsultantCommented:
Just one more suggestion, in order to have the records in the correct category I would suggest that you change the zone to "Software\System Utilities\Remote Access\Citrix" OR "Software\Virtualization\XenServer".
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Ayman BakrSenior ConsultantCommented:
Did disabling TCP/IP Task Offloading help? Please let's have your feedback.
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epaschalAuthor Commented:
Mutawadi,

I am open to trying this, but is there any documentation regarding doing this on the version I'm running (6.0)? Also I still have the issue where memory utilization suddenly stopped reporting in XenCenter.

Thanks.
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Ayman BakrSenior ConsultantCommented:
Unfortunately, I couldn't find any documentation for doing it on XenServer v. 6.0. However, I believe that these are Linux CLI commands that should work in any version. To be on the safe side, is it possible to arrange for a test environment where you can issue these commands on a test XenServer 6.0?

As for the memory utilization you need to verify that you have the correct NTP servers in the list as follows:
1. type 'xsconsole'
2. click 'Network and Management Interface'
3. click 'Network Time (NTP)'

If these are the correct ones then I would suggest that you verify connectivity to NTP server through CLI as follows:
service ntpd restart

You should get 3 green OK as follows:
Shutting down ntpd: [  OK  ]
ntpd: Synchronizing with time server: [  OK  ]
Starting ntpd: [  OK  ]
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epaschalAuthor Commented:
Unfortunately I don't have a test environment, just my production systems.

As for the memory utilization, I will test the NTP items you have suggested and report back.

Thanks.
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Ayman BakrSenior ConsultantCommented:
Is it possible then to XenMotion all your VMs onto the pool master and then Disable the checksum on the freed XenServer? That is capacity wise can any of both your XenServers handle all the VMs?

If so you can then try on the freed server, restart it and verify the results. If that fixes your issues you can then switch the pool maters and do the changes on the other.

You can also issue the 'top' command in CLI of the XenServer to see the processe running and there resource consumption and look for any odd activities. More on the 'top' command:

http://linux.about.com/od/commands/l/blcmdl1_top.htm
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