Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2004-03-05 13:59:53 -0600 \ Curtis Tiffany: > >> Can i club any database with drbd? , can i use "rawdevices" in > >>drbd to avoid any database inconsistency. > > > > > >What do you mean with "inconsistency" here? > > > >Yes, you can. > >With drbd 0.6.X with the restriction that it should not change the > >logical block size too often (best: not at all). > >The drbd is basically just an other block device. > > I'm not sure if this is what he means, but I've assumed that you can not > prevent data inconsistencies in databases mirrored by drbd. > > For instance, > You have an atomic transaction that completes on the primary node that > writes to multiple blocks > While replicating the changes on the secondary, the primary fails > > The database on the secondary, which may become the primary, will have > inconsistent data, right? As long as you use protocol "C", this is NOT true. If some user (file system, database, any program) wants to complete a "transaction", it should make sure that whatever was modified is on stable storage. To do so typically (f)sync is used. With protocol "C" in connected mode, this completes only *after* sync completed on *both*, active AND passive node. So no, any application that is able to cope with a power outage on a standalone box is able to cope with failure of the active node. Only the "reboot" is faster ... Lars Ellenberg