Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Oh and btw this thread is probably more appropriate for the Pacemaker mailing list than DRBD at this point :-)
Jake
----- Original Message -----
From: "Eric Robinson" <eric.robinson at psmnv.com>
To: "Jake Smith" <jsmith at argotec.com>
Cc: drbd-user at lists.linbit.com
Sent: Tuesday, December 11, 2012 4:39:19 PM
Subject: RE: [DRBD-user] FileSystem Resource Won't Start
Jake,
> I believe it goes a little something like this...
> collocate resource B on A.
> Once the cluster has determined where to start A then B can
> start regardless of whether or not A has completed its start action.
> Think of resource A as something that takes 30 seconds to start.
> Then assume resource B requires it to be completely started
> before it can successfully start up.
> Now resource B fails to start... with an exit code that
> non-standard because something it's looking for is missing
> (since resource A isn't started yet) = infinity failure on
> current node.
> This will cause the cluster to move resource B to another
> node except no other nodes have resource A running which
> results in resource B being unable to run on any node.
>
> Add ordering A then B.
> Now the cluster will wait till A finishes starting (or for
> multi-state/DRBD promoting) before starting B on the same node.
> Everyone is happy.
>
> Does that make sense?
>
It does indeed by confirming and bringing definition to the foggy notion that was bouncing around in my head. Thanks for going the extra mile.
FYI, following is what my cluster currently looks like in crm_mon. My next goal is to get a bunch of mysql instances running. About half of the instances will run on each node unless a node fails, in which case one node will run all instances. The mysql instances are all dependent on the underlying filesystem and VIP, but they are not dependent on each other. So I do want the filesystem and VIP to start before any mysql instances do, but I do not especially care what order the mysql instances start in.
--
Online: [ ha09a ha09b ]
Master/Slave Set: ms_drbd0 [p_drbd0]
Masters: [ ha09a ]
Slaves: [ ha09b ]
Master/Slave Set: ms_drbd1 [p_drbd1]
Masters: [ ha09b ]
Slaves: [ ha09a ]
Resource Group: g_clust08
p_fs_clust08 (ocf::heartbeat:Filesystem): Started ha09a
p_vip_clust08 (ocf::heartbeat:IPaddr2): Started ha09a
Resource Group: g_clust09
p_fs_clust09 (ocf::heartbeat:Filesystem): Started ha09b
p_vip_clust09 (ocf::heartbeat:IPaddr2): Started ha09b
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