On Oct 5, 2011, at 11:03 AM, Florian Haas wrote: > 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. >
The problem is not with amount of lines, pacemaker has limitations which I don't see how to solve with your approach. How would you configure dependencies on such "combined" resource? There is no way to express "if one of two is running", unless I miss something. Regards, Vadym _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
