Recently i suddently got serious issues on a SR that contains lots of VM’s

Snapshots did not get created anymore, now my backup system is depending on this, so i took some time to dive into this issue.

I found a forum post on the citrix forums from 19 October 2012 describing the same issue. (http://forums.citrix.com/thread.jspa?threadID=295713&start=0&tstart=0)

Errors are like this:
Error code: SR_BACKEND_FAILURE_181
Error parameters: , Error in Metadata volume operation for SR. opterr=VDI delete operation failed for parameters: /dev/VG_XenStorage-

Now i am not going into the time it takes Citrix to fix this, but i guess anyone with Xenserver 6.0 and Xenserver 6.0.2 can get this issue.
After looking into the forum on Page 3 i found a practical workaround that fixes the problem for now.

My temporary FIX until Citrix published a real hotfix, continue at own risk !
See Official Citrix article regarding this issue here: http://support.citrix.com/article/CTX131660

First you need to exactly know what you are doing, because if done wrong YOU CAN LOOSE VM’S

Tools needed (if on a windows machine):
-Xencenter
-WinSCP
-Good nerves

Open up a winscp session to your Xenserver host (if in a pool, the pool master)
Open the file /opt/xensource/sm/srmetadata.py (backup this file first!)

Change the file according to the post on the forum:

go to line 472
add
sr_info = sr_info.replace(‘&’,'+’)
go to line 492
add this line:
vdi_info = vdi_info.replace(‘&’,'+’)

Now in Xenserver 6.0.2 i did this somewhat different

go to line 472
replace all text with
sr_info = sr_info.replace(‘&’,'+’)

go to line 491
replace all text with
vdi_info = vdi_info.replace(‘&’,'+’)

Save the file and it should then be possible to make snapshots again.