On Wed, May 15, 2019 at 2:32 PM Nicolas Ecarnot <nicolas@ecarnot.net> wrote:

> This can happen when using thin provisioned disks on block storage
> (iSCSI, FC). We provision such disk with 1G, and and extend the disk
> (add 1G) when it becomes too full (by default, free space < 0.5G).
> If we fail to extend the disk quick enough,

"quick enough" -> Is there some place where this threshold can be

it is some time I don't go into it, because I anyway tend to use preallocated disks on block storage, but at 4.0, 4.1 time, when using thin dsks, the parameters and their tested values were these in vdsm.conf section [irs] or in some other file such as /etc/vdsm/vdsm.conf.d/50_thin_block_extension_rules.conf


# Together with volume_utilization_chunk_mb, set the minimal free
# space before a thin provisioned block volume is extended. Use lower
# values to extend earlier.
volume_utilization_percent = 20

# Size of extension chunk in megabytes, and together with
# volume_utilization_percent, set the free space limit. Use higher
# values to extend in bigger chunks.
volume_utilization_chunk_mb = 8192

Crosscheck in 4.2/4.3. Also, I remember I had problems in RHV 4.2 and RHVH hosts trying to customize vdsm.conf, but I didn't deal much with it because I decided then to use preallocated and not use anymore those parameters.

HIH investigating more,