[DRBD-user] qcow2 as drbd-device ?

Yanni M. gianni.milo22 at gmail.com
Wed Apr 21 18:49:44 CEST 2021


On Wed, 21 Apr 2021 at 13:29, <fatcharly at gmx.de> wrote:

> Hi,
> I'm using a drbd 9.13 on CentOS 8 with pacemaker for a mysql-cluster. This
> cluster is running on a kvm/qemu cluster.

You are probably referring to the drbd-utils version as the most current
drbd kernel module version is drbd-9.0.28.

The virtual harddisks for the virtual mysql-nodes are qcow2 devices.
> Is this really a good idea to use qcow2 as base for drbd ?

Since drbd is a block device I would not use qcow2 on top of it, mainly for
performance purposes.I'd rather deploy the VMs directly onto it (raw).

I can see that the qcow2-devices have grown larger as the drives of the
> virtual machines really are right now. Is this normal ?

Do you mean that the size of the qcow2 on the host has grown up larger than
the actual "used" size withing the guest? If yes, then I think that's a
case of correctly configuring the trim or discard support both on the guest
and the host (not related to drbd).

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