Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
> I'm testing and tinkering with DRBD to answer all those 'what if' > questions before we go into production. While doing this I managed > to get a node into the state where it is the Primary and the > SyncTarget at the same time. > > This has got to be a bad thing if you try to mount the FS as > the data > under the fs will change as the sync progresses, right? I see a > great opportunity for data corruption here. > > So, is there a reason why this is even allowed by drbd? I can't see > a situation where it would be needed, does such a situation exist? That's a feature, you don't risk data corruption. In previous versions sync target/source was coupled with primary/secondary state. On boot, this required waiting for all sync operations to finsih before starting heartbeat (or whatever cluster manager you use) so heartbeat could freely choose which devices to make primary. With current drbd, this restriction no longer applies, startup can continue right after connecting the drbd devices. If you make a sync target primary, all reads for out-of-sync data are fetched from the sync source, so the data read off the drbd device stays consistent. Especially in an active/active cluster with multiple drbd devices this greatly reduces risk of long startup delays. Bye, Martin