Host disconnected midway during backup, now unable to start/restart/cancel

Danp

@justjosh Seem to recall running into this issue once before. IIRC, I used this method to resolve the issue --

https://discussions.citrix.com/topic/399028-paused-vdi/#comment-2025338

justjosh

@danp Did you just remove the VDI or took other steps?

Danp

@justjosh I ran the commands from the link I posted to remove the "paused" flag from sm-config

justjosh

@danp Which UUID did you use as the reference? I've used the UUID provided under OpaqueRef but it's saying that UUID is invalid.

>>> vdi_ref = session.xenapi.VDI.get_by_uuid('92d82ecf-f03c-4f6d-9f2f-6d4f8beced23')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/site-packages/XenAPI.py", line 264, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.7/site-packages/XenAPI.py", line 160, in xenapi_request
    result = _parse_result(getattr(self, methodname)(*full_params))
  File "/usr/lib/python2.7/site-packages/XenAPI.py", line 238, in _parse_result
    raise Failure(result['ErrorDescription'])
XenAPI.Failure: ['UUID_INVALID', 'VDI', '92d82ecf-f03c-4f6d-9f2f-6d4f8beced23']

Danp

@justjosh You should be able to get the correct UUID by going to the VM's Disks tab in XO and click the copy icon for the desired disk.

justjosh

@danp I was under the impression I would need to remove the VDI for the snapshot and not the VDI for the VM's disk. Is the remove_from_sm_config command supposed to be run on the VM disk?

Danp

@justjosh Yes, the goal is to 'unpause' the the VDI for the VM's disk.

If you look back at the thread I posted, they showed the output from xe vdi-list uuid=d50a85ca-eda2-4cbd-a348-80c7d6808ac1 params=all, where the UUID was from the VM's disk VDI. You could perform the same on your VDI to confirm that the issue is present in sm-config entry.

justjosh

@danp I've cleared the pause but I'm still encountering errors regarding pause. Any ideas?

I still have a snapshot from 4th Dec when the error first started. Is it safe to delete that? Will the delta backup be able to merge a full snapshot with the existing chain?

 Snapshot 
Start: Dec 8, 2020, 09:15:07 AM
End: Dec 8, 2020, 09:15:08 AM
Error: SR_BACKEND_FAILURE_82(, Failed to snapshot VDI [opterr=failed to pause VDI d11dc884-b91d-4ea0-87ef-6b96ce5b0ad4], )
Start: Dec 8, 2020, 09:15:07 AM
End: Dec 8, 2020, 09:15:08 AM
Duration: a few seconds
Error: SR_BACKEND_FAILURE_82(, Failed to snapshot VDI [opterr=failed to pause VDI d11dc884-b91d-4ea0-87ef-6b96ce5b0ad4], )

Danp

@justjosh Yes, it should be fine to delete the snapshot and then rerun the backup job.

nicolas

@Danp Did you remember what command you used to remove the "paused" flag, as the link from Citrix is not working anymore? Thanks!

nicolas

As I needed it urgently, I wrote a python script which remove the flag from the db with this command :

vdi_ref = session.xenapi.VDI.get_by_uuid(vdi_uuid)
session.xenapi.VDI.remove_from_sm_config(vdi_ref, "paused")

It worked and my vm are back to business!

Danp

@nicolas Yes, that is essentially what was shown in the link. Note: the developers have warned to be careful using this technique because the disk is in a paused state for a reason, so simply clearing the flag could lead to unintended consequences.

Alternatively, you can try running this command --

/opt/xensource/sm/resetvdis.py single <VDI UUID>