[Gluster-users] GlusterFS as virtual machine storage

[Pavel Szalbot]

Hi,

On Thu, Aug 24, 2017 at 2:13 AM, WK <wkmail at bneit.com> wrote:
> The default timeout for most OS versions is 30 seconds and the Gluster
> timeout is 42, so yes you can trigger an RO event.

I get read-only mount within approximately 2 seconds after failed IO.

> Though it is easy enough to raise as Pavel mentioned
>
> # echo 90 > /sys/block/sda/device/timeout

AFAIK this is applicable only for directly attached block devices
(non-virtualized).

> Likewise virtio "disks" don't even have a timeout value that I am aware of
> and I don't recall them being extremely sensitive to disk issues on either
> Gluster, NFS or DAS.

We use only virtio and these problems are persistent - temporarily
suspending a node (e.g. HW or Gluster upgrade, reboot) is very scary,
because we often end up with read-only filesystems on all VMs.

However we use ext4, so I cannot comment on XFS.

This discussion will probably end before I migrate VMs from Gluster to
local storage on our Openstack nodes, but I might run some tests
afterwards and keep you posted.

-ps