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

[Joel Colledge]

Hi Bryan,

> In the very last post in this thread there is this:
>
> "DRBD requires some intervention to enable the volume. The
> simplest method to get the new volume working would be to demote
> the resource to the "Secondary" role and then promote it to the
> "Primary" role again, using drbdadm primary --force resourcename.
> The newly added volume will then perform a full sync and should
> end up "UpToDate" once the sync finishes."

Yes, this is the way to do it at the moment. Doing it without any
downtime is tricky.

> Here I made a very bad mistake.  I issued "pcs cluster standby storage1"
> to put the primary storage into standby mode.  However, with Volume 1
> in an Inconsistent state on both servers, what happened, was that
> storage1 went into secondary mode and storage2 (the secondary server)
> failed to be elevated to primary.  At this point all of our storage went
> off line, with both storage servers in secondary mode.
>
> 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.

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?

Best regards,
Joel