Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2004-03-08 12:32:40 -0500 \ Carson Gaspar: > > > --On Friday, March 05, 2004 21:49:18 +0100 Lars Ellenberg > <Lars.Ellenberg at linbit.com> wrote: > > [ Re: database consistency ] > > >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. > > As I understand it, protocol "B" should also be OK, as long as the > secondary doesn't reboot at the same time, and may improve performance over > protocol "C". What can go wrong, will go wrong, so "Should be OK, as long as" == Is not ok. And, though one might think it has better performance, and it was *intended* to have better performance, benchmarks show that it DOES NOT have better performance. We will eventually find out why, and fix it. Meanwhile: Use protocoll "C", and enjoy transactional semantics *and* best performance for short distance links. "A" is for long distance / high latency links. Using "B" does currently not gain anything, but degrades throughput, and loses transactional semantics, so should be avoided. Lars Ellenberg