Re: Opteron/FreeBSD/PostgreSQL performance poor

On Jul 5, 2006, at 10:43 AM, andy rost wrote:

> We're in the process of porting from Informix 9.4 to PostgreSQL
> 8.1.3. Our PostgreSQL server is an AMD Opteron Dual Core 275 with
> two 2.2 Ghz 64-bit processors. There are two internal drives and an
> external enclosure containing 14 drives (configured as 7 pairs of
> mirrored drives - four pairs for table spaces, one pair for
> dbcluster, two pairs for point in time recovery). The operating
> system is FreeBSD 6.0-RELEASE #10

What RAID card are you hooked up to? My best machines have LSI
MegaRAID 320-2X cards in them, with the pairs of each mirrored set on
opposing channels. My second best machine (into which the above card
will not fit) uses an Adaptec 2230SLP card similarly configured.

The database is mirrored from one box to the other, and a vacuum
analyze takes ~10 hours.

You seem to have done the right things in your postgresql.conf file.

Things I'd like to know before offering advice: how big is your
database? Ie, what is the "df" output for your various partitions
holding Pg data? also, how much RAM is in this box? And finally,
can you show the output of "iostsat -w3" for a few rows during times
when you're having poor performance.