OpenStack (cinder) volumes retyping on Ceph back-end

Andrea Martra andrea.martra at oscct.it
Tue Jun 20 08:57:44 UTC 2023


Hello,
I configured different back-end storage on OpenStack (Yoga release) and using Ceph (ceph version 17.2.4) with different pools (volumes, cloud-basic, shared-hosting-os, shared-hosting-homes,...) for RBD application.
I created different volume types towards each of the backends and everything works perfectly.
If I perform a "change volume type" from OpenStack on volumes attached to the VMs the system successfully migrates the volume from the source pool to the destination pool and at the end of the process the volume is visible in the new pool and is removed from the old pool.
The problem encountered is that when reconfiguring the VM, to specify the new pool associated with the volumes (performed through a resize of the VM, I haven't found any other method to change the information on the nova/cinder db automatically. I also did some tests shut-off of the VM and modification of the xml through virsh edit and startup the VM) the volume presented to the VM is exactly the version and content on the retype date of the volume itself. All data written and modified after the retype is lost.
The VM after the retype continues to work perfectly in RW but the "new" volume created in the new pool is not used to write data and consequently when the VM is shut down all the changes are lost.

Do you have any idea how to carry out a check and possibly how to proceed in order not to lose the data of the vm of which I have retyped the volume?

The data is written somewhere (the IO is still going to the old pool/image although they already have been removed) because the VMs work perfectly.

Thank you

--

Andrea Martra
+39 393 9048451




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