[ClusterLabs] Question on sharing data with DRDB

[JCA]

I sent what follows to the DRDB list, but immediately after doing so I
concluded that this list probably is more apposite. Therefore here it goes,
with my apologies to  those who read both lists.


I am a complete newbie to this, so please bear with me.

I am trying to use DRBD in conjunction with Pacemaker. To this effect, I
have followed the steps specified in chapter 7 of the Pacemaker's "Clusters
from Scratch" document (see here
<https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/2.0/pdf/Clusters_from_Scratch/Pacemaker-2.0-Clusters_from_Scratch-en-US.pdf>
) with a few variations - e.g. instead of using a logical volume, I use an
actual partition (/dev/sdb1) which I formatted with ext4, rather than xfs.

In the terminology of the document above, when I am done with all the steps
I end up with a /dev/drbd1 device in each of pcmk-1 and pcmk-2. The step in
section 7.7 I executed (in pcmk-1) as follows:

     # pcs -f fs_cfg resource create TestFS Filesystem device="/dev/drbd1"
directory="/tmp/Testing"
        fstype="ext4"

Before doing this, I created /tmp/Testing on both pcmk-1 and pcmk-2.

After everything is completed, in pcmk-2 I end up with /tmp/Testing
containing the files that I earlier on copied into the directory to be
shared in pcmk-1, as described in section 7.5. My problem is, how (and
where) do I access those files in pcmk-1? At this point, they don't seem to
be accessible, for I unmounted /dev/drbd1 in pcmk-1, as instructed at the
end of section 7.5. I was hoping to be able to mount it again, in pcmk-1,
but that is not working for me:

      # mount /dev/drbd1 /mnt
      mount: /dev/drbd1 is write-protected, mounting read-only
      mount: mount /dev/drbd1 on /mnt failed: Wrong medium type

What am I doing wrong?
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