Re: SATA drives performance

On 12/24/2009 10:51 AM, Greg Smith wrote:
>> 7. If you have 3 equal disks, try doing some experiments. My inclination
>> would be to set them all up with ext4...
>
> I have yet to yet a single positive thing about using ext4 for
> PostgreSQL. Stick with ext3, where the problems you might run into
> are at least well understood and performance is predictable.
>

Hi Greg:

Can you be more specific? I am using ext4 without problems than I have
discerned - but mostly for smaller databases (~10 databases, one almost
about 1 Gbyte, most under 500 Mbytes).

Is it the delayed allocation feature that is of concern? I believe this
feature is in common with other file systems such as XFS, and provided
that the caller is doing things "properly" according to POSIX and/or the
file system authors understanding of POSIX, which includes
fsync()/fdatasync()/O_DIRECT (which PostgreSQL does?), everything is fine?

File systems failures have been pretty rare for me lately, so it's hard
to say for sure whether my setup is really running well until it does
fail one day and I find out. (Not too concerned, though, as I keep off
site pg_dump backups of the database on a regular schedule - the
databases are small enough to afford this :-) )

Cheers,
mark

--
Mark Mielke<mark(at)mielke(dot)cc>