Re: SSDs with Postgresql?

On Thu, Apr 21, 2011 at 10:33 AM, Florian Weimer <fweimer(at)bfk(dot)de> wrote:

> * Greg Smith:
>
> > The fact that every row update can temporarily use more than 8K means
> > that actual write throughput on the WAL can be shockingly large. The
> > smallest customer I work with regularly has a 50GB database, yet they
> > write 20GB of WAL every day. You can imagine how much WAL is
> > generated daily on systems with terabyte databases.
>
> Interesting. Is there an easy way to monitor WAL traffic in away? It
> does not have to be finegrained, but it might be helpful to know if
> we're doing 10 GB, 100 GB or 1 TB of WAL traffic on a particular
> database, should the question of SSDs ever come up.
>
> If you archive your WAL files, wouldn't that give you a pretty good
indication of write activity?

For example, yesterday I archived 74 WAL files, each 16MB. That's about 1.2
gigabytes for a database that takes up about 58 GB.
--
Mike Nolan