[Pacemaker] Speed up resource failover?

[Lars Ellenberg]

On Wed, Jan 12, 2011 at 09:30:41AM +0100, Robert van Leeuwen wrote:
> -----Original message-----
> To:	pacemaker at oss.clusterlabs.org; 
> From:	Patrick H. <pacemaker at feystorm.net>
> Sent:	Wed 12-01-2011 00:06
> Subject:	[Pacemaker] Speed up resource failover?
> Attachment:	inline.txt
> > As it is right now, pacemaker seems to take a long time (in computer terms) to 
> > fail over resources from one node to the other. Right now, I have 477 IPaddr2 
> > resources evenly distributed among 2 nodes. When I put one node in standby, it 
> > takes approximately 5 minutes to move the half of those from one node to the 
> > other. And before you ask, theyre because of SSL http virtual hosting. I have 
> > no order rules, colocations or anything on those resources, so it should be 
> > able migrate the entire list simultaneously, but it seems to do them 
> > sequentially. Is there any way to make it migrate the resources in parallel? Or 
> > at the very least speed it up?
> 
> Patrick,
> 
> It's probably not so much the cluster suite but is has to do with the specific resource script. 
> For a proper takeover of a IP you have to do an arp "deregister/register".
> This will take a few seconds.
> As long as a resource script is busy the cluster suite will not start the next action.
> Parallel execution is not possible in the cluster suite as far as I know.
> (without being a programmer myself I would expect it is pretty tricky to implement parallelization "code-wise" and making 100% sure the cluster does not break)
> 
> You could consider to edit the IPaddr2 resource script so it does not wait for the arp commands.
> At you're own risk of course ;-)

There is the cluster option "batch-limit" (in the cib), see
"configuration explained".
and there is lrmd "max-children" (can be set in some /etc/defaults/ or
/etc/sysconfig file, should be set by the init script).
you can set it manually with lrmadmin -p max-children $some_number
That should help you a bit.
But don't overdo. Raise them slowly ;-)


-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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