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Xenserver 6.5 VM's running badly. Cant see why. Help please?

Chris ampyuml


Hi really hoping you can help and apologies as I have also asked this question in server installation.


Xencenter v6.5 build 64bit


The install running on a Dell  PowerEdge T430 server and the physical server logs show no issue.

All as far as a I know was working ok until last Friday when users started complaining of performance issue's.


Xen seems fine. All I can see so far is that xencenter reports that the Local storage Ext3 usage is 99%. Have deleted older snapshots but xencenter still reports local storage 99%


Please anyone help??


kind regards

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Yes, you can run manual disk space recovery (a scan) but again, no guaranty it will work if the disk is that full. Upgrading would be a good idea as 65 is long out of support and probably not all that secure. If a VM is consuming 200% of CPU resources, you might consider adding additional vCPUs to the VM to give it more capacity.



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It can take up to 24 hours for space to be recovered after  system scan. However, if the capacity exceeds around 90%, this can prevent the space reclaiming from working.

I the worst case, you may need to move some of the storage to another SR at lest temporarily to free up enough room that the coalescing process can work. That's at least my guess as

to what is happening as far as the storage space is concerned.


I'd also run top and xentop to make sure you are not using up too many dom0 resources. Check for memory and swap space usage, as well as the CPU load.



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Hi Tobias,


Thanks for the reply.


There were only 3 vm's running. The DC which boots to safe mode OK fails to boot and Xentop cpu % for that vm as 200%. It has now been shutdown 

The One other non important vm shutdown as well. Xentop doesn't show anything un toward now. See attached.


Can a manual disk space recovery be run or is that not recommended?


Kind regards


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Thanks Alan - I appreciate is old and I have mentioned it to them


@Tobias The reclaim freed space option in xencetner is grayed out and Im not sure how to do a manual scan is that option for non Ext3 sr's? 

How would I do a manual search. sorry not being lazy just under a lot of pressure currently :(


Help appreciated

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Under XS 6.5 run:

xe sr-scan uuid=sr_uuid

whre sr_uuid is the UUID of the SR to be scanned.


As to why the scan option would be grayed out, it might be because this will only work on thinly provisioned volumes. If that's the case, you will have to shuffle your storage around to be able to gain back space.



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Many thanks both for taking the time out to assist me with this problem. Much appreciated.


I can confirm that after exporting the VM's for safety and deleting some of the snapshots (The SR usage  still showed 99% in Xen center) the automated coalescence of the local SR worked. As of this morning Xencenter showed usage as 78% :)


All VM's booted and after some house keeping, as of now, are running as they should.


Yes, I believe the scan option in Xencerter is grayed out because online coalesce is not supported for Ext3 types 


Kind regards and thanks

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Great to hear that things are better now! Typically, the coalesce seems to stop working reliably once you hit about the 90% of physical capacity. In such cases, it is indeed necessary to move some VMS around (you don't even have to export them, just migrate the VDIs over to a different SR, which however should never be done if these are associated with XenDesktop VMs!) which will free up space on the SR in question.

And, yes, that makes sense with the ext SR being grayed out.


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