Sent: Tue Dec 14 2010 11:37:06 GMT-0700 (Mountain Standard Time)
From: Dejan Muhamedagic <deja...@fastmail.fm>
To: The Pacemaker cluster resource manager <pacemaker@oss.clusterlabs.org>
Subject: Re: [Pacemaker] continue starting chain with failed group
resources
Hi,
On Mon, Dec 13, 2010 at 10:43:36PM -0700, Patrick H. wrote:
After tinkering with this for a few hours I finally have something working.
colocation co-raid inf: ( md_raid iscsi_1 iscsi_2 iscsi_3 )
This should be noop. You'd want something like this, I think:
colocation co-raid inf: md_raid ( iscsi_1 iscsi_2 iscsi_3 )
No, that makes the md_raid service depend on all the iscsi services
being started, which I dont want
order or-raid 0: ( iscsi_1 iscsi_2 iscsi_3 ) md_raid
Got rid of the group, changed the score on the order to 0, and
changed the grouping of both the colocation and order. This
*appears* to function as intended, but if anyone can point out any
pitfalls I'd appreciate it
-Patrick
Sent: Mon Dec 13 2010 21:12:04 GMT-0700 (Mountain Standard Time)
From: Patrick H. <pacema...@feystorm.net>
To: The Pacemaker cluster resource manager <pacemaker@oss.clusterlabs.org>
Subject: [Pacemaker] continue starting chain with failed group resources
Is there a way to continue down a chain of starting resources once
a previous resource hast tried to start, no matter if the try was
successful or not?
No, that's currently not possible to express. I think that you
should take the iSCSI resources out of the cluster and let them
start on boot _before_ the cluster manager. If there are not
enough disks, then the md_raid resource is going to fail.
Cant do that either. When the node that is currently using the iscsi
services fails, they have to be migrated over to another host so it can
assemble them into a raid array. If theyre not being managed by
pacemaker, they wont migrate.
I made a few more tweaks from the configuration I posted earlier and it
seems to work pretty good with only one exception.
colocation co-raid inf: ( md_raid iscsi_1 iscsi_2 iscsi_3 )
order or-raid_start 0: ( iscsi_1:start iscsi_2:start iscsi_3:start )
md_raid:start
order or-raid_stop inf: md_raid:stop ( iscsi_1:stop iscsi_2:stop
iscsi_3:stop )
That makes it so that when they start up, they start in order, but it
isnt required that every iscsi start before md_raid, just that they try
to start
Then when they stop, its manditory that they stop in that order so that
no iscsi service will stop while md_raid is still running.
The exception I mentioned is a bug in the policy engine. Bug 2435. The
policy engine allows resources within a colocation set to start on other
nodes. So if I were to stop one of the iscsi services, and then start it
again, it might start on a different node. Unless this bug gets fixed
soon, I'll probably modify the iscsi script so that all the iscsi
devices are under 1 resource.
Thanks,
Dejan
I've got 3 iSCSI resources which are in a group, and then an md
raid-5 array as another resource. I have the raid array resource
set to start after the group with a colocation rule, but it will
only start if the whole group comes up. Since this is raid-5, we
can obviously handle some disk failure and start up anyway. So how
do I get it to try to start it up once all the iSCSI resources
have tried to start? Went looking through the docs and didnt find
anything.
Note: there will be other resources in the chain (like mounting
the filesystem) that I dont want to try and start if the raid
array resource didnt start.
------------------------------------------------------------------------
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_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
