[Pacemaker] Pacemaker DRBD as Physical Volume on Encrypted RAID1

[senrabdet at aol.com]

Hi All:

We're new to pacemaker (just got some great help from this forum getting it working with LVM as backing device), and would like to explore the Physical Volume option. We're trying configure on top of an existing Encrypted RAID1 set up and employ LVM.

NOTE:  our goal is to run many virtual servers, each in its own logical volume and it looks like putting LVM on top of the DRBD would allow us to add logical volumes "on the fly", but also have a "simpler" setup with one drbd device for all the logical volumes and one related pacemaker config.  Hence, exploring DRBD as a physical volume.

Q:  For pacemaker to work, how do we do the DRBD disk/device mapping in the drbd.conf file?  And should we set things up and encrypt last, or can we apply DRBD and Pacemaker to an existing Encypted RAID1 setup?

The examples we've seen show mapping between the drbd device and a physical disk (e.g., sdb) in the drbd.conf, and then  "pvcreate /dev/drbdnum" and creating a volume group and logical volume on the drbd device.

So for this type of set up, drbd.conf might look like:

device    /dev/drbd1;    
disk      /dev/sdb;
address xx.xx.xx.xx:7789;
    meta-disk internal;

In our case, because we have an existing RAID1 (md2) and it's encrypted (md2_crypt or /dev/dm-7 ...  we're unsure which partition actually has the data), any thoughts on how to do the DRBD mapping?  E.g., 

device /dev/drbd1 minor 1;
disk /dev/???????;
address xx.xx.xx.xx:7789; 
meta-disk internal;

I.e., what goes in the "disk /dev/?????;"?  Would it be "disk /dev/md2_crypt;"?

And can we do our setup on an existing Encrypted RAID1 setup (if we do pvcreate on drbd1, we get errors)?

Thanks!

Ted
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