Re: optimal hardware for postgres?

The first thing you need to do is assess where your bottleneck is
going to be.  Is it RAM? or CPU or IO?  If your system is IO bound,
you are better off spending your $s on a good IO controller and lots
of drives that racking up the $$s with Expensive Opteron 275s or 250s,
when a 242 would do the job just fine for les than $200 ea.

The Tyan S2885 mobo is a good chioce for a rig, it's not too expense,
and has 2 independant PCI buses if you want to run two seperate
controlers, which if you are going to run both database and webserver
on one box I would heartily recommend doing.  Run the webserver on a
RAID 1 on the first controler with WAL on another RAID 1, then run
your DB on the other controller with a 4 or 6 drive RAID 10 (This is
what you might want to look at if you are IO bound).

This kind of server can be built for $4-7k in either SCSI or SATA
configs depending on your preference/budget/size requirements.  SCSI
is a bit more, but you get better performance, SATA raptor has good
performance, and gives you more space for your dollar if you don't
mind going SATA (plus if you use multi-lane with 3ware controller you
get a reasonable number of cables instead of spaghetti junction).

Don't bother with Xeon, the performance has been shown to be pathetic
relative to Opteron for Postgresql and also not as cost effective.

Check out the size of your data set, and your search requirement.  The
more data you can cache in RAM the better off you will be, and the
quicker you will move the bottleneck from IO to RAM/CPU (It looks like
you will be read intensive not write from your comments).  If you need
more RAM, put it in as it can save on the disk cost, and you can go
with a generic 4U chasis instead of an expensive chasis with backplace
built in.  Antec has a nice 4U that has 8 drive bays that will fit
2x3U 4 drive modules for 8 drives total plus room for a CD ROM to
spare.  If you need more than this check out rackmountmart.com.  They
have a nice 4U and 5U chasis that has lots of space for drives.

Thats my 0.02

Alex Turner
netEconomist

On 4/24/05, peter pilsl <pilsl@goldfisch.at> wrote:
>
> I'm just going to buy a new server which will mainly run a
> postgreSQL-database and a apache2 with mod_perl and do little more than
> deliver loads of index-based select-queries. But it will have to do a
> lot of them. And it will be master for a replication to slaves.
> As always of course we dont know how many selects we'll have to face.
> There will be "many" and the current Athlon1800+ with 1GB Ram is too
> slow. (to its excuse : It has to perform loads of other tasks as well)
>
> I was now wondering which hardware would fit this server best. I think
> about 2GB RAM, a fast Raid1 and now I'm not sure about the CPU.
> I was considering 64-bit AMD : A Athlon 64 FX-51 or a Opteron 2.2GHz.
> The hosting system will be a 64-Bit linux.
>
> Does postgres benefit from 64-bit AMD's or would I be better off with a
> cheaper AthlonXP or even with a Pentium or a more expensive Xeon?
> Or is my question faulty at all, cause CPU is only 20% of the whole system.
>
> Any comments appretiated,
> thnx,
> peter
>
> --
> mag. peter pilsl
> goldfisch.at
> IT-management
> tel +43 699 1 3574035
> fae +43 699 4 3574035
> pilsl@goldfisch.at
>
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