Re: Ideal hardware configuration for pgsql - Mailing list pgsql-general

  Since I'd rather have a screwdriver than a compiler, I'll jump in on a
response to the original message....

> Our db server running 7.1 got *torched* today, system ran between 30% an
> 80% CPU all day!  Right now the server is running on a Penguin Computing
> 800mhz PIII w/ 128 ram and IDE hardware.
>
> Tomorrow I'd like to place an order for something more robust... looking
> into dual PIII, gig of ram and SCSI Raid.  Planning on running Red Hat 7.1
> on this machine.
>
> Before I order, I was wondering if anyone had any suggestions or
> recommendations.  I have been considering getting a Sun machine... but I
> don't know if there is a benefit.  Also, are there any special
> considerations when running RAID and dual CPU?
>
> You're input is tremendously appreciated!

   I'll address the questions in a hap-hazard order....

1.  Sun hardware?  The benefit of Sun hardware is when you need a greater
sheer capacity than you can get with the higher-end Intel systems.  Of
course, Alphas are also a good thing to consider when you're in that range.
In a single- or dual-cpu system, Intel systems do fine unless you're just
looking to burn money, offering a better price/performance ratio, and
*possibly* higher overall performance compared to a single/dual Sun or
Alpha.

  (If you don't like that last statement, I'm sorry.  In my experience, that
has *occasionally* been the case.)

2.  Disk type - use SCSI, not IDE.  IDE takes too much CPU.  If you're just
trying to copy a file, that's not bad - but if you're trying to process DB
queries at the same time, it's bad.

3.  RAID - it's a great thing for speed and redundancy.  Our main DB server
uses a RAID 5 array with a "hot spare".  Since we have enough RAM to keep
the DB files in cache, though, the speed isn't that much of a factor, the
disk lights only blink occasionally.  Having cache on the RAID controller
also helps alleviate disk writes.   If you don't need the redundancy, you
can get very good speed improvements by just using a lot of RAM and turning
off fsync() - that way, you don't hit the disks much at all.

4.  CPU's - you may not need a 1 GHz.  Find the "sweet spot", which is
probably an 866 or 933.  The difference won't be that great.  If the
difference between a 933 and a 1 GHz chip is going to make or break it, you
probably need a quad-CPU solution to allow for growth and expansion.

5.  Motherboard - if you want dual P3's, and more than 512 MB of RAM,
consider the Asus CUV4X-D boards, we use several of them, and they're
terrific, stable performers.

    Once you've got a gig of RAM and you're using SCSI disks (preferably
RAID), the CPU's tend to be the bottleneck.  On our system (4 Xeon 700's,
RAID, 512 MB), the disk lights only blink *occasionally*, and we have
hundreds of megs of file cache, no swapping.  We're going to increase the
RAM soon, but that's only because our database is going to grow
considerably, and we want to make sure that we keep all of the DB files in
disk cache.   In terms of price-for-performance, Suns and Alphas aren't even
in the same ballpark as this machine.  Of course, Intel hardware can only
take you so far, and then Suns, Alphas, and the like are the only options.

steve