Re: Portworx snapshots - Mailing list pgsql-general

From Stephen Frost
Subject Re: Portworx snapshots
Date
Msg-id 20181030152136.GQ4184@tamriel.snowman.net
Whole thread Raw
In response to Re: Portworx snapshots  (Laurenz Albe <laurenz.albe@cybertec.at>)
List pgsql-general
Greetings,

* Laurenz Albe (laurenz.albe@cybertec.at) wrote:
> Stephen Frost wrote:
> > The downside with any snapshot-style approach is that it means that when
> > you have a failure, you have to go through and replay all the WAL since
> > the last checkpoint, which is single-threaded and can take a large
> > amount of time.
> >
> > When doing your testing, I'd strongly recommend that you have a large
> > max_wal_size, run a large pgbench which writes a lot of data, and see
> > how long a failover takes with this system.
>
> Then "checkpoint_timeout" should also be large, right?

Having a larger checkpoint timeout would also show that this method of
failover runs the risk of there being a very long time required between
when the failure is detected and when the new primary is online.

Thanks!

Stephen

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