Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Helmut Wollmersdorfer a écrit : > Jason Gray schrieb: > >> I'm looking at creating a multi-clustered array server network for our >> production environment. Is it possible to have 5,6,7..n servers >> clustered >> together (kind of like a token ring) to act as redundant arrays for each >> other? > > > DRBD is a two node cluster. > You can have something like this: > > Node1 Node2 Node3 > ----- ----- ----- > drbd1 Primary Secondary > drbd2 Secondary Primary > drbd3 Primary Secondary > drbd4 Secondary Primary > >> So, instead of having a Primary array I would have 5,6 or 7 "Primary" >> arrays >> that mirror each other across an isolated network (10.0.0.0 say). > > > Not each to each. > > You can build a "chain": > > Situation 1: > > Node1 Node2 Node3 > ----- ----- ----- > drbd1 Primary Secondary stopped > > Then switch to Situation 2: > > Node1 Node2 Node3 > ----- ----- ----- > drbd1 stopped Primary Secondary I'll keep this message, you explain very clearly what the situation is. > > This sort of switchover will take time, because Node3 needs to sync with > Node2. In case of a full sync of e.g. 100 GB this will need _hours_. Good point. So, what would be your recommendation here ? I see three possible cases in case Node1 fails: -CASE1 I think I can repair Node1, and resynch it with updates only after repair. Therefore I decide not to synchronize Node3 as a secondary -CASE2 I think I cannot repair Node1, or it then will require a full sync anyway. Therefore I decide to synchronize Node3 as a secondary -CASE3 I don't know why Node1 is down. I start sync to Node3 as soon as possible, then I see what I can get from Node1. If I repair it shortly, then, I'll stop synching Node3 and resynch Node1. I made noise for nothing during this period of time. Shaman-X today implementation is CASE3: start sync automatically and change secondary manually. Maybe we should think about a human decision to implement CASE1. We might also give a chance to auto-repair Node1, something like: if Node1 is not back before 10mn, or if Node1 is unstable and failed three times in the last 24h, etc... then we go automated and we sync a new secondary. Any opinion ? Dominique > > Helmut Wollmersdorfer > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > >