Re: Shopping for hardware

On Mon, 6 Oct 2003, Jason Hihn wrote:

> Ok, I asked this on [novice], but I was told it's be better to post it
> here...
>
> I've got some money to spend on a new servers. The biggest concern is the
> PostgreSQL database server that will "be the company." (*Everyone* uses the
> database server in some form or another) I'm looking for hot-swappable RAID
> 1 on a Linux platform at the least. Are there any vendors to avoid or
> prefer? What works best? Am I better off going with a DIY or getting
> something pre-packaged?

Depends on your hardware expertise.  You can do quite well either way.  I
prefer adding my own components to a pre-built vanilla server.

> In terms of numbers, we expect have an average of 100 active connections
> (most of which are idle 9/10ths of the time), with about 85% reading
> traffic.  I hope to have one server host about 1000-2000 active databases,
> with the largest being about 60 meg (no blobs). Inactive databases will only
> be for reading (archival) purposes, and will seldom be accessed. (I could
> probably move them off to another server with a r/o disk...)

That's not a really big load, but I'm guessing the peaks will be big
enough to notice.

> Does any of this represent a problem for Postgres? The datasets are
> typically not that large, only a few queries on a few databases ever return
> over 1000 rows.

Nah, this is pretty normal stuff for Postgresql or any other database in
its approximate class (Sybase, Oracle, Informix, DB2, MSSQL2k).

> The configuration that is going on in my head is:
> RAID 1, 200gig disks
> 1 server, 4g ram
> Linux 2.4 or 2.6 (depends on when we deploy and 2.6's track record at that
> time)

That's a good starting point.  I'd avoid 2.6 until it's had time for the
bugs to drop out.  The latest 2.4 kernels are pretty stable.

List of things to include if you need more performance, in order of
priority:

proper tuning of the postgresql.conf file (see
http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html)
hardware RAID card with battery backed cache, the bigger the cache the
better.
more drives for RAID 1+0
faster CPUs.

since you've already got 4 gigs of RAM slated, you're set there on linux,
where having more won't likely help a lot unless you go to a 64 bit
platform.

> I want something that can do hot-swaps and auto-mirroring after swap.
> Unfortunately, this is a new area for me. (I normally stick to S/W for
> non-high end systems)

The LSI/Megaraid cards can handle hot swaps quite well, make sure you get
the right kind of hot swap shoes so they isolate the drive from the buss
when you turn it off and they don't lock up your scsi buss.