Gerhard Hintermayer <gerhard.hintermayer@gmail.com> wrote:
> I'm trying to set up at least 3 servers using hot standby
> streaming replication. I'd like to have one primary and 2
> secondary (on 2 different locations in case of a desaster in the
> server room).
> A primary
> B secondary 1
> C secondary 2 (on a different location that A and B)
>
> Are the following actions in case of recovering to any of the
> standby servers (B or C) correct ?
>
> 1. primary A crashes/maintenance or whatever
> 2. creating the trigger file on B brings this server to life.
> 3. stop server on C
> 4. make base backup on B and install it on C and A (if already
> available)
> 5. change primary_conninfo in recovery.conf on A,C to reflect new
> primary B
> 6. start server on A,C
>
> These actions should all be automated, since I have no redundancy
> between step 1 and 6, so in case something happens to the just
> switched over new primary, I have no up to date server to bring up
> from standby. Making base backup takes ~10 mins, installing
> probably also about 10 mins, so I have 20 minutes, where nothing
> should happen to B :-(
>
> But maybe I'm also missing something.
The main thing I would look at is how you do step 4. Proper use of
rsync (using a daemon) directly from B to C and A (over the top of
what they have from before the crash) should be optimal. We saw two
orders of magnitude improvement in backup time over a slow WAN doing
this. YMMV
-Kevin