[DRBD-user] Adding a second volume to a resource and making it UpToDate

[Bryan K. Walton]

On Tue, Aug 31, 2021 at 01:58:24PM +0200, Joel Colledge wrote:
> > So, maybe this is a question for the Pacemaker mailing list, but what
> > did I do wrong here?  When adding a second volume to a resource, what is
> > the proper way to change its state from Inconsistent to UpToDate?
> 
> I would say that you're on the right track, but put Pacemaker into
> maintenance mode while making the changes.

Thank you for your reply, Joel!  I'm a little confused.  If I understand 
you correctly, what I should have done is:

pcs property set maintenance-mode=true
pcs cluster standby storage1

How would the combination of putting Pacemaker in maintenance mode and
then trying to standby a cluster member work?  Or maybe what you are
saying is that the standby command would have not really done anything
(because maintenance mode was active), but running the command and
then running the unstandby command would have been enough to trigger a
change in the "Inconsistent" state?


> Taking a step back - why do you need to add a second volume to a
> resource which is in use? Multiple volumes are used to form
> consistency groups. For instance, placing database logs and tables on
> different backing storage. When you do that you generally know at the
> time you set it up, so there is no need to add a second volume to a
> resource which is in use. Is there any reason you can't just create a
> second DRBD resource for your new volume?

In hindsight, I probably should have used a second resource.  The core
issue that I'm addressing is that we are running Red Hat Enterprise
Virtualization on top of DRBD/Pacemaker.  We are planning an upgrade to
RHEV 4.4 which requires a new storage domain in RHEV.  And we had no
free space in our iSCSI environment to use for a new storage domain.
So, we added new drives to our storage servers.

Thanks,
Bryan