[ovirt-users] VM has paused due to no storage space error

[Nir Soffer]

On Sun, Oct 2, 2016 at 12:06 PM, Sandvik Agustin
<agustinsandvik at gmail.com> wrote:
> Hi users,
>
> I have this problem that sometimes 1 to 3 VM just automatically paused with
> user interaction and getting this error "VM has paused due to no storage
> space error". any inputs from you guys are very appreciated.

This is expected - when there is no storage space :-)

The vm is paused when there are some io pending io requests that
could not be fulfilled since you don't have enough space.

In a real machine the io requests would fail. In a vm, the vm can pause,
you can fix the issue (extend the storage domain), and resume the vm.

But I guess there is storage space available, otherwise you would
not spend the time sending this mail.

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, the vm will pause before the
extend was completed. Once the extend was completed, we resume
the vm.

So you may see very short pauses, but they should be rare.

To understand the issue, we need to inspect vdsm logs from the host
running the vm that paused, showing the timeframe when the vm
was paused.

You should see this message in the log each time a vm pauses:

    abnormal vm stop device <devname> error ENOSPC

Nir