XenServer 5.5 Release Upgrade Notes01 Jul
While most transitions to XenServer 5.5 are proceeding seamlessly, there are a few snags being encountered by the bleeding-edge adopters. Contact DedicatedIT today, 561-491-5725, with questions and concerns about your XenServer 5.5 Upgrade.
XenServer 5.5 VDI Sizes
Citrix has always been straightforward about their supported limit of a maximum 2TB size for a single VDI. However, previously to 5.5, it was possible to create larger LVM-based VDIs. Users that have upgraded to 5.5 have discovered that they are no longer able to mount those huge VDIs to their VMs. Citrix has its highest-level engineers on it, but Citrites aren’t promising anything yet.
‘SR Backend Failed’ Errors
Another problem relates to VMs not being able to start after the pool upgrade is complete – XenCenter returns:
The SR backend failed to complete the operation.
Resolutions do not appear to be consistent at this moment. Some are successful by just forgetting and attaching the SR, while other users find success by refreshing the 5.5 install on the pool master.
Guest Network Performance Problems
Some users have reported a big drop in guest network performance after updating Xen Tools on the guests. So far, the only resolution has been to uninstall the Tools package.
VM Snapshot Considerations
Many users are making the early jump to 5.5 in order to have the ability to create snapshots of any VM on any SR type. The downside to this is that your VDIs will be converted to VHD. This will have an impact on performance because a filesystem is being introduced to the SR – how much of an impact is yet to be determined. Additionally, VHD files have a hard 2TB limit. Also, creating the snapshot requires an amount of freespace equal to the size of the VDIs being snapped. It appears that the privileged domain isn’t creating a delta file but instead replicating the base file.
As we discover more, we’ll add them here. Also, if you’ve had any ‘fun’ experiences upgrading to 5.5 in your shop, let us know!
Cheers,
~Phil
3 Responses to “XenServer 5.5 Release Upgrade Notes”
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I’m running several webservers in Xen 5.5 and am having network performance issues. Has there been any updates to the network slowness? File transfer to the server is not a problem, but from the server is a big difference.
The fix: (at least in my case)
On all Xen 5.5 hosts:
xe pif-param-set uuid= other-config:ethtool-tx=”off”
xe pif-param-set uuid= other-config:ethtool-rx=”off”
Not needed, but may have been beneficial for other things:
xe pif-param-set uuid= other-config:ethtool-speed=1000
xe pif-param-set uuid= other-config:ethtool-duplex=”full”
Reboot Hosts
On all VM’s running 2003:
Start regedit
Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Create a new DWORD value called DisableLargeSendOffload, and set it to 1.
Create a new DWORD value called DisableTaskOffload, and set it to 1.
Reboot.
Hunter,
Thank you very much for the recommendation. Do you have any metrics as far as improvement in your environment goes?
Would you recommend this for all people, or just people with a specific problem?