On Fri, Oct 26, 2018 at 10:07 PM Markus Stockhausen <stockhausen@collogia.de> wrote:

we observed high count of getVolumeSize() calls in vdsm.log Looking
at the logs it seems as if this is done every minute for all disk that
are currently running on a node.

Is this frequency normal and if yes why?

Yes, this is expected.

Vdsm is monitoring volume size every 60 seconds, based on this

configuration:

https://github.com/oVirt/vdsm/blob/cbdbee979f0bfc7a7dd447af0d69c5aa9e0f8b8c/lib/vdsm/common/config.py.in#L369

The monitoring is needed to update engine about disk actual size when

using thin provisioning.

- With block storage, when vdsm detect that a disk is too full, it will extend the disk with help

of the SPM host.

- With sparse disks on file storage, the disk actual size will grow as the VM writes more

data to the disk.

Engine show the actual disk size based on the size reported by vdsm, using data collected by

these getVolumeSize calls.

This check can probably optimized to run only on file based thin provisioned disks instead of

any disk. Please file a bug to optimize this is you think it is an issue.

Nir