On Wed, 2009-06-24 at 07:22 -0700, nate wrote: > Kris Buytaert wrote: > > > > > > We're trying to setup a dual-primary DRBD environment, with a shared > > disk with either OCFS2 or GFS. The environment is a Centos 5.3 with > > DRBD82 (but also tried with DRBD83 from testing) . > > Both OCFS2 and GFS are meant to be used on SANs with shared storage(same > LUNs being accessed by multiple servers), I just re-confirmed that DRBD > is not a shared storage mechanism but just a simple block mirroring > technology between a couple of nodes(as I originally thought). Actually, it's both. http://www.drbd.org/users-guide-emb/ch-fundamentals.html gives the overview. It's shared storage with local disk access. And if you're using Gig-E for the interconnect, it's *fast*. ;) > I think you are mixing incompatible technologies. Even if you can > get it working, just seems like a really bad idea. That functionality is built in. DRBD fully supports use of OCFS2 on top of it in dual-primary mode. See http://www.drbd.org/users-guide-emb/ch-ocfs2.html > Perhaps what you could do is setup an iSCSI initiator on your DRBD > cluster, export a LUN to another cluster running OCFS2 or GFS(last I > checked GFS required at least 3 nodes less than that and the cluster > goes to read-only mode, I didn't see any minimum requirements for > OCFS2). You could do that, but it would probably be overkill. Too many moving parts. You'd also slow down the speed. You're talking about app node -> Gig-E -> OCFS2/GFS cluster -> Gig-E -> iSCSI/DRBD cluster. I'd rather have app node -> Gig-E -> OCFS2/DRBD cluster. And it's *much* easier to setup. GFS is a bit of a pita to setup. I used to do it for RH professionally and it's not entirely painless... > Though the whole concept of DRBD just screams to me crap performance > compared to a real shared storage system, wouldn't touch it with > a 50 foot pole myself. Nah... performance is pretty sweet. Local disk access, sub-second resync after rebooting one of the nodes, and the cost is *much* lower than a "real" shared-storage system... if cost is a factor, I'd seriously consider trialing the DRBD/OCFS2 combo.