Re: best arrangement of 3 disks for (insert) performance

rj(at)last(dot)fm (Richard Jones) writes:
> I have some new hardware on the way and would like some advice on
> how to get the most out of it..
>
> its a dual xeon 2.4, 4gb ram and 3x identical 15k rpm scsi disks
>
> should i mirror 2 of the disks for postgres data, and use the 3rd
> disk for the o/s and the pg logs or raid5 the 3 disks or even stripe
> 2 disks for pg and use the 3rd for o/s,logs,backups ?
>
> the machine will be dealing with lots of inserts, basically as many
> as we can throw at it

Having WAL on a separate drive from the database would be something of
a win. I'd buy that 1 disk for OS+WAL and then RAID [something]
across the other two drives for the database would be pretty helpful.

After doing some [loose] benchmarking, the VERY best way to improve
performance would involve a RAID controller with battery-backed cache.

On a box with similar configuration to yours, it took ~3h for a
particular set of data to load; on another one with battery-backed
cache (and a dozen fast SCSI drives :-)), the same data took as little
as 6 minutes to load. The BIG effect seemed to come from the
controller.
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Christopher Browne
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