Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi list, in my endless search for information :) I was testing DRBD in dual primary mode + GFS2. The goal is "the same": running a replicated, 2-node KVM setup where disk images are located on the GFS2 filesystem. I know how to integrate DRBD with corosync/pacemaker, but I wonder how the system will perform under load. More specifically, it is my understanding that GFS2 inevitably has some significan overhead compared to a traditional, one-node filesystem, and this can lead to decreased performance. This should be especially true when restarting (or live-migrate) a virtual machine on the other host: as the first node has cached significan portion of the vm disk, GFS2 will, on every first read on the new host, fire its coherency protocol to be sure to update the first's node in-memory cached data. The overhead should be lowered by not using cache at all (ie: cache=none, which implies O_DIRECT), but this will also case degraded peformance in the common case (ie: when all is working correctly and VMs run on the first node only). So I ask: has some of you direct experience with a similar setup? How do you feel about? Any other suggestions? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti at assyoma.it - info at assyoma.it GPG public key ID: FF5F32A8