Also, consider DRBD [LWN.net]

Also, consider DRBD

Posted Jun 4, 2012 10:08 UTC (Mon) by niner (subscriber, #26151)
In reply to: Also, consider DRBD by andresfreund
Parent article: Clustering, development, and galactic conquest at PGCon 2012

That's not entirely true. If your DRBD device is on top of LVM you can take a snapshot and mount this snapshot even on the secondary. We use such a setup for backups and it works just fine. You could even run PostgreSQL on this snapshot and do your reports from it.

Of course LVM snapshots have their own performance problems and just using PostgreSQL's native replication might be easier and faster, but still just using DRBD is a possibility which allows to cover not just the database.

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Also, consider DRBD

Posted Jun 4, 2012 10:36 UTC (Mon) by andresfreund (subscriber, #69562) [Link]

Sure, you can do that or similar things (loads of SANs have that capability). Keeping the secondary pg instance up2date is really expensive in that scenario though. You need to shutdown pg, drop old, create new snapshot, start pg which will do recovery. If you have nontrivial amounts of writes the wal replay uppon startup will take quite some time....
I don't really see any reason to do so these days unless your database is gigantonormous and you cannot afford to have a full copy of the datadir for reporting.