[ClusterLabs] DLM, cLVM, GFS2 and OCFS2 managed by systemd instead of crm ?

[Ken Gaillot]

On Tue, 2019-10-15 at 21:35 +0200, Lentes, Bernd wrote:
> Hi,
> 
> i'm a big fan of simple solutions (KISS).
> Currently i have DLM, cLVM, GFS2 and OCFS2 managed by pacemaker.
> They all are fundamental prerequisites for my resources (Virtual
> Domains).
> To configure them i used clones and groups.
> Why not having them managed by systemd to make the cluster setup more
> overseeable ?
> 
> Is there a strong reason that pacemaker cares about them ?
> 
> Bernd 

Either approach is reasonable. The advantages of keeping them in
pacemaker are:

- Service-aware recurring monitor (if OCF)

- If one of those components fails, pacemaker will know to try to
recover everything in the group from that point, and if necessary,
fence the node and recover the virtual domain elsewhere (if they're in
systemd, pacemaker will only know that the virtual domain has failed,
and likely keep trying to restart it fruitlessly)

- Convenience of things like putting a node in standby mode, and
checking resource status on all nodes with one command

If you do move them to systemd, be sure to use the resource-agents-deps 
target to ensure they're started before pacemaker and stopped after
pacemaker.
-- 
Ken Gaillot <kgaillot at redhat.com>