Re: filesystem option tuning

Shridhar Daithankar <shridhar@frodo.hserus.net> writes:
> On Wednesday 19 May 2004 13:02, share-postgres@think42.com wrote:
> - If you can put WAL on separate disk(s), all the better.
>>
>> Does that mean only the xlog, or also the clog?

> You can put clog and xlog on same drive.

You can, but I think you shouldn't.  The entire argument for giving xlog
its own drive revolves around the fact that xlog is written
sequentially, and so if it has its own spindle then you have near-zero
seek requirements.  As soon as you give that drive any other work to do,
you start losing the low-seek property.

Now as Shridhar says, clog is not a very high-I/O-volume thing, so in
one sense it doesn't much matter which drive you put it on.  But it
seems to me that clog acts much more like ordinary table files than it
acts like xlog.

            regards, tom lane