[Pacemaker] resources not migrating when some are not runnable on one node, maybe because of groups or master/slave clones?
Phil Frost
phil at macprofessionals.com
Mon Jun 18 14:38:44 UTC 2012
On 06/18/2012 10:05 AM, Jake Smith wrote:
> Why don't you have vg_nfsexports in the group? Not really any point to
> a group with only one resource...
> You need an order constraint here too... Pacemaker needs to know in
> what order to start/stop/promote things. Something like: order
> ord_drbd_master_first drbd_nfsexports_ms:promote vg_nfsexports:start
> test:start
Indeed, a group with one resource isn't useful, but this is a minimal
test case, not a practical configuration. My understanding is that
putting just one resource in a group, though not a useful thing to do,
should be a no-op with respect to how that resource is placed in the
cluster. This is because a group is intended to be a shorthand for order
and colocation constraints among the group, and in a group of 1, there
is nothing to constrain. In this case, the presence of the group, which
should do nothing but does, suggests to me a bug in the constraint logic
or my understanding of group semantics.
Regarding the order constraint, I don't think it is necessary, because
Dummy resources can start in any order they please. Indeed if they were
actually the services the names suggested they would need the order
constraint, and I did have them in my full configuration, but in my
attempt to reduce the problem I determined that the order constraint had
no effect on the undesirable behavior, so I removed it.
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