On 2011-10-05 16:44, Vadym Chepkov wrote: > > On Oct 5, 2011, at 9:38 AM, Florian Haas wrote: > >> On 2011-10-05 14:59, Vadym Chepkov wrote: >>> Hi, >>> >>> It looks like iscsi multipath IO is not supported by iscsi RA. >>> What would be the proper way to configure iSCSI MPIO in a pacemaker cluster? >> >> OK, so first of all are you absolutely positive you _must_ use MPIO? >> Most users find it much easier to just run their iSCSI initiator over a >> bonded network interface if all you want to protect against is network >> failure. >> > > This could start a holy war, but this is configuration which is recommended > by Dell and, furthermore , not all storages have bonding capabilities, but, > usually, they do have multiple ethernet interfaces.
Granted, if you want completely separate paths from your nodes to the storage boxes, then the bonding approach doesn't get you too far. Still, for most users protecting against failure of one uplink path is sufficient, and bonding does do nicely at that. >> Secondly, you can always define two iscsi resources that Pacemaker >> manages via ocf:heartbeat:iscsi. Then as soon as those come online, >> provided the SCSI target sets consistent serial numbers and SCSI IDs, >> multipathd should happily put them together as one mpath device. In your >> configuration, does it not do that? >> > > This would create a very complicated configuration. You have to colocate both > resources and you can't use inf: in colocation because it would break > redundancy (all or nothing) Well, "inf colocation constraint breaks redundancy" is an exaggeration, but I think I see what you mean. I'm still thinking an advisory colocation constraint would help you achieve what you need, though. > I guess lsb:iscsi RA is the only option. I wonder how that makes the setup less complicated. So you've got one resource that manages all of your iSCSI connections. Then what if one of them fails? Do you ignore that? Do you reconnect all of them? What if not all of them fail, but two that make up the same mpath device? Correct, your Pacemaker configuration has a few lines less, but you're signing up for massive headaches if things go wrong. Things, that is, that Pacemaker could fix for you automatically. Cheers, Florian -- Need help with High Availability? http://www.hastexo.com/now _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
