Re: Hardware advice

Based on what you've said, I would guess you are considering the Dell PowerEdge 2650 since it has 5 drive bays. If you could afford the rackspace and just a bit more money, I'd get the tower configuration 2600 with 6 drive bays (and rack rails if needed - Dell even gives you a special rackmount faceplate if you order a tower with rack rails). This would allow you to have this configuration, which I think would be about ideal for the price range you are looking at:

* Linux kernel RAID
* Dual processors - better than a single faster processor, especially with concurrent user load and software RAID on top of that
* 2x36GB in RAID-1 (for OS and WAL)
* 4x146GB in RAID-10 (for data) (alternative: 4-disk RAID-5)

The RAID-10 array gives you the same amount of space you would have with a 3-disk RAID-5 and improved fault tolerance. Although I'm pretty sure your drives won't be hot-swappable with the software RAID - I've never actually had to do it.

I can't say I like Scott's idea much because the WAL and OS are competing for disk time with the data since they are on the same physical disk. In a database that is mainly reads with few writes, this wouldn't be such a problem though.

Just my inexpert opinion,

Roman

-----Original Message-----
From: Adam Witney [mailto:awitney(at)sghms(dot)ac(dot)uk]
Sent: Fri 5/30/2003 9:55 AM
To: scott.marlowe; Adam Witney
Cc: pgsql-performance
Subject: Re: [PERFORM] Hardware advice

Hi scott,

Thanks for the info

> You might wanna do something like go to all 146 gig drives, put a mirror
> set on the first 20 or so gigs for the OS, and then use the remainder
> (5x120gig or so ) to make your RAID5. The more drives in a RAID5 the
> better, generally, up to about 8 or 12 as the optimal for most setups.

I am not quite sure I understand what you mean here... Do you mean take 20Gb
from each of the 5 drives to setup a 20Gb RAID 1 device? Or just from the
first 2 drives?

Thanks again for your help

adam


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