Ron wrote:

At 08:37 AM 8/30/2005, Alvaro Nunes Melo wrote:


We are about to install a new PostgreSQL server, and despite of being a very humble configuration compared to the ones we see in the list, it's the biggest one we've got till now.

The server is a Dual Xeon 3.0 with 2 GB RAM and two SCSI disks. Our main doubt is what is the best configuration for the disks. We are thinking about use them in a RAID-0 array. Is this the best option? What do you suggest on partitioning? Separate partitions for the OS, data and pg_xlog?

This is _very_ modest HW. Unless your DB and/or DB load is similarly modest, you are not going to be happy with the performance of your DBMS.

Well that is a pretty blanket statement. I have many customers who happily run in less hardware that what is mentioned above.
It all depends on the application itself and how the database is utilized.

At a minimum, for safety reasons you want 4 HDs: 2 for a RAID 1 set for the DB, and 2 for a RAID 1 set for the OS + pg_xlog. 2 extra HDs, even SCSI HDs, is cheap. Especially when compared to the cost of corrupted or lost data.

Your real test is going to be prototyping the performance you need. A single RAID 1 mirror (don't use RAID 0) may be more than enough. However based on the fact that you speced Xeons my guess is you spent money on CPUs when you should have
spent money on hard drives.

If you still have the budget, I would suggest considering either what Ron suggested or possibly using a 4 drive RAID 10 instead.

If you can't afford to put a couple more SCSI disks it may be worth while to put a software RAID 1 with ATA disks for the OS and swap and then use straight SCSI hardware RAID 1 for the DB. That will allow you to push any swap operations off to the OS disks
without sacrificing the performance and reliability of the database itself.


Joshua D. Drake

HD's and RAM are cheap enough that you should be able to upgrade in more ways, but do at least that "upgrade"!

Beyond that, the best ways to spend you limited $ are highly dependent on your exact DB and its usage pattern.

Ron Peacetree

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