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

Christian Rohmann christian.rohmann at
Sun Feb 14 23:52:52 UTC 2021

Hello Openstack-Discuss,

after some digging I found out that cinder learned to resize attached 
(in-use) volumes quite a while ago with the introduction
of the initial "extend 'in-use' volume" feature:

The support was then extended to also cover Ceph RBD backed volumes with:

Since this is only about the cinder part, I was wondering if nova would 
ever find out and would actively rescan the device / volume and 
quintessentially present an increased new size to the guest. Apparently 
this is where a certain volume-extended event comes into play: that is to be 
emitted by cinder when a volume had been extened.

I then went head and tried this with the openstack cli (as Horizon does 
not seem to support / offer to resize in-use volumes.
I run Openstack Train with Ceph RBD as storage. First I ran into an 
issue with the openstack cli 
<>) but using

   cinder extend $volumeid $newsize

I was able to resize in-use volumes just fine.

The only thing missing was the propagation to the guest. I played around 
with SCSI rescans, but that did not work, reboots also failed to do 
anyting in this regards. Stopping and starting the VM did work, but why 
having the capability to online-resize an attached volume when not being 
able to resize the guest volume as well?

Apparently there seems to be an old and somewhat similar observation / 
bug with

So I was simply wondering if this is expected to be working?
Are there any special settings / options I need to set to enable this 

Thanks and with kind regards


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the openstack-discuss mailing list