On Thu, Mar 29, 2012 at 8:35 AM, Andrew Beekhof <and...@beekhof.net> wrote: > On Thu, Mar 29, 2012 at 5:28 PM, Vladislav Bogdanov > <bub...@hoster-ok.com> wrote: >> Hi Andrew, all, >> >> Pacemaker restarts resources when resource they depend on (ordering >> only, no colocation) is migrated. >> >> I mean that when I do crm resource migrate lustre, I get >> >> LogActions: Migrate lustre#011(Started lustre03-left -> lustre04-left) >> LogActions: Restart mgs#011(Started lustre01-left) >> >> I only have one ordering constraint for these two resources: >> >> order mgs-after-lustre inf: lustre:start mgs:start >> >> This reminds me what have been with reload in a past (dependent resource >> restart when "lower" resource is reloaded). >> >> Shouldn't this be changed? Migration usually means that service is not >> interrupted... > > Is that strictly true? Always?
No. Few things are always true. :) However, see below. > My understanding was although A thinks the migration happens > instantaneously, it is in fact more likely to be pause+migrate+resume > and during that time anyone trying to talk to A during that time is > going to be disappointed. I tend to be with Vladislav on this one. The thing that most people would expect from a "live migration" is that it's interruption free. And what allow-migrate was first implemented for (iirc), live migrations for Xen, does fulfill that expectation. Same thing is true for live migrations in libvirt/KVM, and I think anyone would expect essentially the same thing from checkpoint/restore migrations where they're available. So I guess it's reasonable to assume that if one resource migrates, dependent resources need not be restarted. But since Pacemaker now does restart them, you might need to figure out a way to preserve the existing functionality for users who rely on that. Not sure if any do, though. Cheers, Florian -- Need help with High Availability? http://www.hastexo.com/now _______________________________________________ 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://bugs.clusterlabs.org
