[DRBD-user] drbd 8.4.7 out-of-sync on disabled host page cache in VM

[acs at sysgo.com]

> On 13 March 2019 at 11:47 Roland Kammerer <roland.kammerer at linbit.com> wrote:
> 
> 
> On Tue, Mar 12, 2019 at 09:08:42AM +0100, Armin Schindler wrote:
> > On 3/11/19 1:42 PM, Roland Kammerer wrote:
> > > On Mon, Mar 11, 2019 at 11:13:11AM +0100, Armin Schindler wrote:
> > >> 2 hosts Debian 9 (stretch) with default DRBD version 8.4.7.
> > > 
> > > Please retry with the current 8.4.11 version of DRBD. You can it from
> > > here:
> > > https://www.linbit.com/en/drbd-community/drbd-download/
> > 
> > Okay, thanks. I will test 8.4.11.
> > 
> > Do I need to change/update the tools as well or just the kernel driver?
> > I currently use drbd-utils 8.9.10.
> 
> They should be fine. I don't remember any non-corner cases fixes for 8.4
> in drbd-utils.

I tried version 8.4.11 and the problem persists.
When using Qemu/KVM virtio disk with a caching mode that uses host page cache,
or when using just a filesystem like ext4 on (without Qemu/KVM) on the host, the
drbd device gets out of sync after a while.
The drbd device is on top of a LVM-lv on both nodes.

Is there anything else I can test?
According to some (old) posts, this is a known issue for a long time now. But I never
found any resolution or fix.

Thanks.
Armin