This bug is Invalid for Nova and needs to be fixed in Cinder.
** Changed in: nova
Status: In Progress => Invalid
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https://bugs.launchpad.net/bugs/1989514
Title:
NFS volume snapshot does not update volume attachment format to qcow2
Status in Cinder:
In Progress
Status in OpenStack Compute (nova):
Invalid
Bug description:
This was reported downstream when a customer hit the issue [1].
They found that after performing a volume snapshot on a stopped
instance, that instance could no longer boot.
The instance XML had the correct disk format "qcow2" after the
snapshot while it was still stopped. However, when someone then tries
to start the instance, the regenerated XML contains the wrong disk
format "raw" (nova regenerates fresh XML on hard reboot, boot from
shutoff) and that prevents the instance from booting.
While tracing the issue I noticed that after the snapshot, the volume
attachment still showed the format "raw". It should have been "qcow2"
after the snapshot, I think.
The customer found that rebuilding the instance resulted in a booting
instance despite the underlying volume (snapshot) being the same.
Rebuild generates a new volume attachment and that volume attachment
reflected the correct format "qcow2".
Based on this, it appeared to me that volume attachment format was not
being updated from "raw" to "qcow2" after the volume snapshot was
created as qcow2 and was made the active volume for the instance.
AFAICT, there is not a way for nova to update the volume attachment
format.
Repro steps:
$ openstack volume create --image
f8e5b23e-b1d3-44e8-bc71-ac7aca4f6f8e --size 1 --bootable my_volume
$ openstack server create --flavor c1 --volume my_volume --network
private --wait my_server
$ openstack server stop d97a6178-112d-487b-ba21-1af2a4a78456
(Instance has disk format "raw" and volume attachment also shows format
"raw")
(To check this:
$ virsh dumpxml d97a6178-112d-487b-ba21-1af2a4a78456
$ openstack --os-volume-api-version 3.27 volume attachment show
2f43581f-ba30-423e-ba5f-7b0ac7768fa5 -f json
)
$ openstack volume snapshot create --volume d5c71e24-46ac-49be-
bf33-667598b6058b --force my_volume_snapshot
(Instance has correct disk format "qcow2" at this point, volume
attachment shows format "raw")
$ openstack server start d97a6178-112d-487b-ba21-1af2a4a78456
(Instance now has incorrect disk format "raw" and volume attachment
still shows format "raw")
To see the effect of a rebuild:
$ openstack server rebuild d97a6178-112d-487b-ba21-1af2a4a78456
--image f8e5b23e-b1d3-44e8-bc71-ac7aca4f6f8e --wait
(Instance has disk format "qcow2" and volume attachment also shows format
"qcow2")
(Volume attachment is newly created with new ID etc)
[1] https://bugzilla.redhat.com/show_bug.cgi?id=2118150
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