Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Sun, Nov 15, 2009 at 01:08:30AM -0500, Jiann-Ming Su wrote: > Don't know if this has been discussed before, but it seems like with > 8.3's dual primary support, it's possible to set up a 3-node, all > active drbd cluster. > > Each node would be dual primary with each other node. Node A would > form drbd0 with node B and drbd1 with node C. Node B would have drbd0 > with A and drbd2 with C. And, C would have drbd1 with A and drbd2 > with B. > > Then you can use software raid to create md0 on each node with its > respective drbd devices. > > Noce A: md0 (drbd0, drbd1) > Node B: md0 (drbd0, drbd2) > Node C: md0 (drbd1, drbd2) > > Then format md0 on each node with a cluster filesystem like ocfs2 with > each node as a member of the cluster. > > Do the drbd experts here have any thoughts on how this idea would go > horribly wrong? Thanks for any input and feedback. A-MD(A-DRBD0(A-sdx), A-DRBD1(A-sdy)) B-MD(B-DRBD0(B-sdx), B-DRBD2(B-sdy)) C-MD( C-DRBD1(C-sdx), C-DRBD2(C-sdy)) So you write block N on A-MD. It will hit A-DRBD0, and A-DRBD1, which will hit local disks A-sdx, A-sdy, and via DRBD replication B-sdx, and C-sdx. Still with me? Great. Now, you want to read that block N on B, which decides in its read balancing path to fetch block N from B-sdy. It will surely get _some_ data from there, but certainly not the data you just wrote on A-MD. To summ it up in one word: DON'T. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed