[Pacemaker] migration-threshold causing unnecessary restart of underlying resources

Dejan Muhamedagic dejanmm at fastmail.fm
Mon Aug 16 11:29:05 UTC 2010 

Hi,

On Sat, Aug 14, 2010 at 06:26:58AM +0200, Cnut Jansen wrote:
>  Hi,
> 
> and first of all thanks for answering so far.
> 
> 
> Am 12.08.2010 18:46, schrieb Dejan Muhamedagic:
> >
> >The migration-threshold shouldn't in any way influence resources
> >which don't depend on the resource which fails over. Couldn't
> >reproduce it here with our example RAs.
> Well, I now - just to clearly assure that something's wrong there;
> whatever it is, simple misconfiguration or possible bug - did crm
> configure erase, completely restarted both nodes, and then setup
> this new, very simple, dummy-based configuration:
> v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v
> v v v v v v
> node alpha \
>         attributes standby="off"
> node beta \
>         attributes standby="off"
> primitive dlm ocf:heartbeat:Dummy
> primitive drbd ocf:heartbeat:Dummy
> primitive mount ocf:heartbeat:Dummy
> primitive mysql ocf:heartbeat:Dummy \
>         meta migration-threshold="3" failure-timeout="40"
> primitive o2cb ocf:heartbeat:Dummy
> location cli-prefer-mount mount \
>         rule $id="cli-prefer-rule-mount" inf: #uname eq alpha
> colocation colocMysql inf: mysql mount
> order orderMysql inf: mount mysql
> property $id="cib-bootstrap-options" \
>         dc-version="1.0.9-unknown" \
>         cluster-infrastructure="openais" \
>         expected-quorum-votes="2" \
>         stonith-enabled="false" \
>         cluster-recheck-interval="150" \
>         last-lrm-refresh="1281751924"
> ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
> ^ ^ ^ ^ ^ ^
> ...and then, with picking on the resource "mysql", got this:
> 
> 1) alpha: FC(mysql)=0, crm_resource -F -r mysql -H alpha
> Aug 14 04:15:30 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_asyncmon_0 (call=48, rc=1, cib-update=563,
> confirmed=false) unknown error
> Aug 14 04:15:30 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=49, rc=0, cib-update=565,
> confirmed=true) ok
> Aug 14 04:15:30 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=50, rc=0, cib-update=567,
> confirmed=true) ok
> 
> 2) alpha: FC(mysql)=1, crm_resource -F -r mysql -H alpha
> Aug 14 04:15:42 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_asyncmon_0 (call=51, rc=1, cib-update=568,
> confirmed=false) unknown error
> Aug 14 04:15:42 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=52, rc=0, cib-update=572,
> confirmed=true) ok
> Aug 14 04:15:42 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=53, rc=0, cib-update=573,
> confirmed=true) ok
> 
> 3) alpha: FC(mysql)=2, crm_resource -F -r mysql -H alpha
> Aug 14 04:15:56 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_asyncmon_0 (call=54, rc=1, cib-update=574,
> confirmed=false) unknown error
> Aug 14 04:15:56 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=55, rc=0, cib-update=576,
> confirmed=true) ok
> Aug 14 04:15:56 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mount_stop_0 (call=56, rc=0, cib-update=578,
> confirmed=true) ok
> beta: (FC(mysql)=3
> Aug 14 04:15:56 beta crmd: [868]: info: process_lrm_event: LRM
> operation mount_start_0 (call=36, rc=0, cib-update=92,
> confirmed=true) ok
> Aug 14 04:15:56 beta crmd: [868]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=37, rc=0, cib-update=93,
> confirmed=true) ok
> Aug 14 04:18:26 beta crmd: [868]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=38, rc=0, cib-update=94,
> confirmed=true) ok
> Aug 14 04:18:26 beta crmd: [868]: info: process_lrm_event: LRM
> operation mount_stop_0 (call=39, rc=0, cib-update=95,
> confirmed=true) ok
> alpha: FC(mysql)=3
> Aug 14 04:18:26 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mount_start_0 (call=57, rc=0, cib-update=580,
> confirmed=true) ok
> Aug 14 04:18:26 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=58, rc=0, cib-update=581,
> confirmed=true) ok
> 
> 
> So it seems that - for what reason ever - those constrainted
> resources are considered and treated just as they were in a
> resource-group, because they move to where they all can run, instead
> of the "eat or die" for the dependent resource (mysql) to the
> underlying resource (mount) that I had expected with such
> constraints as I set them... shouldn't I?! o_O

Yes, those two constraints are equivalent to a group.

> And - concerning the failure-timeout - quite a while later, without
> having resetted mysql's failure counter or having done anything else
> in the meantime:
> 
> 4) alpha: FC(mysql)=3, crm_resource -F -r mysql -H alpha
> Aug 14 04:44:47 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_asyncmon_0 (call=59, rc=1, cib-update=592,
> confirmed=false) unknown error
> Aug 14 04:44:47 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=60, rc=0, cib-update=596,
> confirmed=true) ok
> Aug 14 04:44:47 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mount_stop_0 (call=61, rc=0, cib-update=597,
> confirmed=true) ok
> beta: FC(mysql)=0
> Aug 14 04:44:47 beta crmd: [868]: info: process_lrm_event: LRM
> operation mount_start_0 (call=40, rc=0, cib-update=96,
> confirmed=true) ok
> Aug 14 04:44:47 beta crmd: [868]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=41, rc=0, cib-update=97,
> confirmed=true) ok
> Aug 14 04:47:17 beta crmd: [868]: info: process_lrm_event: LRM
> operation mysql_stop_0 (call=42, rc=0, cib-update=98,
> confirmed=true) ok
> Aug 14 04:47:17 beta crmd: [868]: info: process_lrm_event: LRM
> operation mount_stop_0 (call=43, rc=0, cib-update=99,
> confirmed=true) ok
> alpha: FC(mysql)=4
> Aug 14 04:47:17 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mount_start_0 (call=62, rc=0, cib-update=599,
> confirmed=true) ok
> Aug 14 04:47:17 alpha crmd: [900]: info: process_lrm_event: LRM
> operation mysql_start_0 (call=63, rc=0, cib-update=600,
> confirmed=true) ok

This worked as expected, i.e. after the 150s cluster-recheck
interval the resources were started at alpha.

> >BTW, what's the point of cloneMountMysql? If it can run only
> >where drbd is master, then it can run on one node only:
> >
> >colocation colocMountMysql_drbd inf: cloneMountMysql msDrbdMysql:Master
> >order orderMountMysql_drbd inf: msDrbdMysql:promote cloneMountMysql:start
> It's a dual-primary-DRBD-configuration, so there are actually - when
> everything is ok (-; - 2 masters of each DRBD-multistate-resource...
> even though I admit that at least the dual primary respectively
> master for msDrbdMysql is currently (quite) redundant, since in the
> current cluster configuration there's only one, primitive
> MySQL-resource and thus there'd be no inevitable need for MySQL's
> data-dir being mounted all time on both nodes.
> But since it's not harmful to have it mounted on the other node too,
> and since msDrbdOpencms and msDrbdShared need to be mounted on both
> nodes and since I put the complete installation and configuration of
> the cluster into flexibly configurable shell-scripts, it's easier
> respectively done with less typing to just put all DRBD- and
> mount-resources' configuration into just one common loop. (-;

OK. It did cross my mind that it may be a dual-master drbd.

Your configuration is large. If you are going to run that in
producetion and don't really need a dual-master, then it'd be
good to get rid of the ocfs2 bits to make maintenance easier.

> >>d) I also have the impression that fail-counters don't get reset
> >>after their failure-timeout, because when migration-threshold=3 is
> >>set, upon every(!) following picking-on those issues occure, even
> >>when I've waited for nearly 5 minutes (with failure-timeout=90)
> >>without any touching the cluster
> >That seems to be a bug though I couldn't reproduce it with a
> >simple configuration.
> I just also tested this once again: It seems like that
> failure-timeout only sets back scores from -inf to around 0
> (whereever they should normally be), allowing the resources to
> return back to the node. I tested with setting a location constraint
> for the underlying resource (see configuration): After the
> failure-timeout has been completed, on the next cluster-recheck (and
> only then!) the underlying resource and its dependants return to the
> underlying resource's prefered location, as you see in logs above.

The count gets reset, but the cluster acts on it only after the
cluster-recheck-interval, unless something else makes the cluster
calculate new scores.

Thanks,

Dejan

> 
> 
> 
> 
> 
> 
> 
> 
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