Re: warm standby - apply wal archives

On September 5, 2011, MirrorX <mirrorx(at)gmail(dot)com> wrote:
> thx a lot for your answer.
>
> actually DRBD is the solution i am trying to avoid, since i think the
> performance is degrading a lot (i ve used it in the past). and also i
> have serious doubts if the data is corrupted in case of the master's
> failure, if not all blocks have been replicated to they secondary. has
> anyone faced this situation? any comments on that? thx in advance
>

DRBD mode C is very good. If you're running mode C, when PostgreSQL issues
an fsync, that doesn't return until the secondary node has the data on disk.
It's as safe as you're going to get.

The performance limit for DRBD is the write speed of a single network
interface. If you're exceeding that, though, you also aren't going to be
shipping out WAL segments in real time. I guess also if your nodes aren't
close by, the latency could be a speed killer, but that's not really the
normal use case.