On Wed, Mar 10, 2010 at 6:59 PM, Martin Aspeli <optilude+li...@gmail.com> wrote: > Serge Dubrouski wrote: >> >> On Wed, Mar 10, 2010 at 5:30 PM, Martin Aspeli<optilude+li...@gmail.com> >> wrote: >>> >>> Martin Aspeli wrote: >>>> >>>> Hi folks, >>>> >>>> Let's say have a two-node cluster with DRBD and OCFS2, with a database >>>> server that's supposed to be active on one node at a time, using the >>>> OCFS2 partition for its data store. >>>> >>>> If we detect a failure on the active node and fail the database over to >>>> the other node, we need to fence off the shared storage in case the >>>> active node is still writing to it. >>>> >>>> Can this be done in such a way that the local DRBD/OCFS2 refuses to >>>> accept writes from the now-presumed-dead node? I guess this would be >>>> similar to putting an access rule on a SAN to block off the previously >>>> active node from attempting to read or write any data. >>>> >>>> Is this feasible? >>> >>> We went off on a side-track, I think, but I'd still like to know the >>> answer: >>> Can one "fence" at the DRBD level? >>> >>> From the thread, it sounds like we'll not use OCFS2 for the Postgres >>> data >>> store, but would still use DRBD, e.g. with ext4 or whatever. The fencing >>> problem would then be equally, if not more, acute. >>> >>> It's basically between doing something at the DRBD level, if that's >>> feasible, or using the DRAC IPMI device on our server to shoot it. >> >> But if you implement fencing on Pacemaker level and include your >> DRBD/Filesystem resource into Pacemaker configuration you'll be fine. > > Sorry, I don't quite understand what you mean. > > What would "fencing on the Pacemaker level" look like? Certainly, DRBD would > be managed by the cluster. >
That means that you have to implement STONITH through DRAC or any other device that will provide fencing capability. In this case if Pacemaker detects a split-brain situation it'll kill one of the nodes. -- Serge Dubrouski. _______________________________________________ Pacemaker mailing list Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker
