Re: Hardware selection

Ron thank you for your comments, sorry of the slow response - i
actually replied to you on saturday but i think the list was having
trouble again?!

Your questions are answered below...

> On Fri, 2003-07-25 at 07:42, psql-mail@freeuk.com wrote:
> > As mentioned previously I have a large text database with upwards
of
>
> > 40GB of data and 8 million tuples.
> >
> > The time has come to buy some real hardware for it.
> >
> > Having read around the subject online I see the general idea is to

> get
> > as much memory and the fastest I/O possible.
> >
> > The buget for the server is approx 20K GBP / 30K US$
> >
> > The data will be stored on an external raid,
> > SCSI based 2.5TB with IDE disks. Configured as 1 large volume,
RAID5.
> (
> > We already have this hardware)
>
> There's a SCSI-IDE bridge somewhere in there?

The raid hardware takes care of it, IDE disks slot into the backplane,
the RAID then SCSI attached to the server.

If this hardware is percieved to be the bottleneck - and i think it
might be, then whats the best thing to replace it with? (a few
different specs/prices would be very helpful!)

> 40GB of data, and 2.5TB disk space??  Even with RAID1+0, that's
> 1.25TB usable; 40GB (even after accounting for overhead and indexes)
> would get lost in 1250GB.  Planning for growth, or also storing lots
> of non-DB related files (which is not a good idea)?

Data is currently 40GB, maybe a bit more, it will increase steadily in
the future. There will be no non-database files on there.

I am also planning to do a full text index on the data so that will
take up alot of room.


> > Question 1 - whats the best raid configuration for this device?
>
> What's your read-to-write ratio?

Faily small bulk INSERTS every 30 mins.
Continous querying within office hours.

> Few complex multi-table queries, lots of simple queries, or
> a mixture?

Mostley queries of the form 'ILIKE "%chicken%"' across >= 30GB of data.
This may change if full text indexing is sucessful but will still be
required for phrases 'ILIKE "%chicken and chips%"

There will also be lots of smaller queries going on  constantly, but
these are already quick enough on the old hardware.

> > Onto the server, I have currently priced up the following:
> > Dell Poweredge 6650
> > 16GB RAM
> > Quad intel hyperthreaded arch
> > PERC3Q controller
> > 36GB System HDD
> > approx 20K UKP
>
> Because of the limits of the x86 architecture, with 16GB RAM, I'd
> really think about a 64 bit system.  Opteron, Alpha, Power5,
> Sparc64, etc.
>
> You can put 16GB RAM in x86 systems, but 64 bit systems use it
> more efficiently.

I was under the impression that both the O/S and the application (
postmaster) needed to be optimised   to make best use of 64 bit arch.
Is this impression wrong? If not, is postgresql optimised for 64bit
arch?


> > Question 2 - Comments and opinions on this as the postgresql server.

>
> > Any comments on better alternatives or modification to this system

> > would be very helpful!
> >
> > Question 3 - what would be the best way to distribute tables/swap/
> > system disk space?
>
> 16GB swap would fit nicely on the system disk.  Hope it's on a
> separate channel from the DB...

Will put the swap on the local disk and the data on the external RAID -
different channels.

> What OS are you using?
I will be using Red hat advanced server 2.1 - thats not set in stone
yet but RH is the distro that I am most familiar with.

Thanks for you help so far!

PS. Just in case theres an amazing system for 60K or less point it out
in case i can get more funding!

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