[pve-devel] Default cache mode for VM hard drives

Stanislav German-Evtushenko ginermail at gmail.com
Thu Nov 20 08:15:51 CET 2014


On Thu, Nov 20, 2014 at 10:11 AM, Dietmar Maurer <dietmar at proxmox.com>
wrote:

> > > Sorry, but we use "cache=none", so cache is not enabled (what cache do
> you
> > talk exactly?).
> > Cache=none means no host cache but backend cache is still in use. In
> case of
> > DRBD this is a buffer in DRBD. So O_DIRECT return OK when data reaches
> this
> > buffer and not RAID cache.
>
> Yes, so DRBD gets the data, and kvm send sync request when required. So I
> still not
> see the problem.
>
Can you also reproduce the problems if you use DRBD device directly,
> without LVM on top?
>

Yes, it is reproducible without LVM.
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