[ClusterLabs] Best DRBD Setup

Brian Jenkins tenethor at gmail.com
Wed Apr 26 15:12:42 EDT 2023

Hi all

I’ve been working on my home cluster setup for a while now and tried varying setups for DRBD resources and finally settled on one that I think is the best but I’m still not completely satisfied with the results. Biggest question is, did I set this up in the best way? Any advice would be appreciated. I have multiple servers setup in groups and the DRBDs are in separate clones like below. I added constraints to hopefully ensure things work together well. If you have any questions to clarify my setup let me know.

* Resource Group: git-server:
* gitea-mount (ocf:heartbeat:Filesystem): Started node1
* git-ip (ocf:heartbeat:IPaddr2): Started node1
* gitea (systemd:gitea): Started node1
* backup-gitea (systemd:backupgitea.timer): Started node1
* Resource Group: pihole-server:
* pihole-mount (ocf:heartbeat:Filesystem): Started node2
* pihole-ip (ocf:heartbeat:IPaddr2): Started node2
* pihole-ftl (systemd:pihole-FTL): Started node2
* pihole-web (systemd:lighttpd): Started node2
* pihole-cron (ocf:heartbeat:symlink): Started node2
* pihole-backup (systemd:backupDRBD at pihole.timer): Started node2
* Clone Set: drbd-gitea-clone [drbd-gitea] (promotable):
* Promoted: [ node1 ]
* Unpromoted: [ node2 node3 node4 node5 ]
* Clone Set: drbd-pihole-clone [drbd-pihole] (promotable):
* Promoted: [ node2 ]
* Unpromoted: [ node1 node3 node4 node5 ]

Ordering Constraints:
start drbd-gitea-clone then start gitea-mount (kind:Mandatory)
start drbd-pihole-clone then start pihole-mount (kind:Mandatory)

Colocation Constraints:
pihole-server with drbd-pihole-clone (score:INFINITY) (rsc-role:Started) (with-rsc-role:Promoted)
git-server with drbd-gitea-clone (score:INFINITY) (rsc-role:Started) (with-rsc-role:Promoted)

My setup is on five raspberry pis running ubuntu server 22.10 with:
pacemaker 2.1.4-2ubuntu1
pcs 0.11.3-1ubuntu1
drbd 9.2.2-1ppa1~jammy1

Overall the setup works but it seems quite fragile. I suffer from lots of fencing whenever I reboot a server and it doesn’t want to restart correctly. Another thing I have noticed is that it will sometimes take as long as 10-12 minutes to mount one of the DRBD filesystems (XFS) so I have extended the start timeout for each *-mount to 15 minutes.
Thanks in advance for any advice to improve the setup.
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