Nova not updating to new size of an extended in-use / attached cinder volume (Ceph RBD) to guest

Christian Rohmann christian.rohmann at
Wed May 5 15:34:12 UTC 2021

Hello all,

On 16/02/2021 22:32, Christian Rohmann wrote:
> I have just been trying to reproduce the issue, but in all my new 
> attempts it just worked as expected:
>> [162262.926512] sd 0:0:0:1: Capacity data has changed
>> [162262.932868] sd 0:0:0:1: [sdb] 6291456 512-byte logical blocks: 
>> (3.22 GB/3.00 GiB)
>> [162262.933061] sdb: detected capacity change from 2147483648 to 
>> 3221225472

On 17/02/2021 09:43, Tobias Urdin wrote:
> Regarding the actual extending of in-use volumes, we had an issue 
> where cinder could not talk to os-server-external-events endpoint for 
> nova because it used the wrong endpoint when looking up in keystone. 
> We saw the error in cinder-volume.log except for that I can't remember 
> we did anything special.
> Had to use newer microversion for cinder when using CLI.
> cinder --os-volume-api-version 3.42 extend <volume ID or name> <new 
> size in GB>

I am very sorry for the delay, but I was now finally able to reproduce 
the issue and with a VERY strange finding:


* When using the cinder client with a Volume API version >= 3.42  like 
you suggested Tobias, it works just fine using cloud admin credentials.
* The volume is attached / in-use, but it is resized just fine, 
including the notification of the kernel on the VM.


* When attempting the same thing using the project users credentials the 
resize also works just fine, volume still attached and in-use, but then 
the VM is NOT notified
* Also this does not seems to be related to nova or QEMU, but rather it 
appears there is no extend_volume event triggered or at least logged:

--- cut ---
Request ID  -- Action -- Start Time -- User ID -- Message

req-a4065b2d-1b77-4c5a-bf53-a2967b574fa0     extend_volume May 5, 2021, 
1:22 p.m.     784bd2a5b82c3b31eb56ee     -
req-5965910b-874f-4c7a-ab61-32d1a080d1b2     attach_volume     
May 5, 
2021, 1:09 p.m.     4b2abc14e511a7c0b10c     -
req-75ef5bd3-75d3-4146-84eb-1809789b6586     Create     May 5, 2021, 
1:09 p.m.     4b2abc14e511a7c0b10c     -
--- cut ---

UserID "784bd2a5b82c3b31eb56ee" is the regular user creating and 
attaching the volume. But that user also did an extend_volume, which is 
not logged as an event.
There also was no API errors reported back to the client, the resize did 
happen - just not propagated to the VM - so a stop and restart was required.

But the admin user with id "4b2abc14e511a7c0b10c" doing a resize attempt 
caused an extend_volume and consequently did trigger a notification of 
the VM,
just as expected and documented in regards to this feature.

Does anybody have any idea what could cause this or where to look for 
more details?


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