Re: 3 x PostgreSQL in cluster/redunant

On Tue, Nov 15, 2005 at 07:38:06PM +0100, Michelle Konzack wrote:
> Am 2005-11-14 16:54:41, schrieb Jim C. Nasby:
> > On Mon, Nov 14, 2005 at 07:36:44PM +0100, Michelle Konzack wrote:
> > > Hello *,
> > >
> > > I have three Sun Server where I have reserved on each Server a Raid-5
> > > of 1 TByte for my PostgreSQL.  The first PostgreSQL is up and running
> > > with a database of 150 GByte.
> >
> > Keep in mind that databases and RAID5 generally don't mix very well.
>
> Can you explain me why?

You'll be better off googling for "raid5 performance", but in a nutshell
write performance on raid5 is horrible. If you database is read-only
then that shouldn't be an issue, but as soon as you start writing much
at all you'll probably be unhappy with the performance.

As for hardware, what is your application? If your choice is between
SCSI raid5 and SATA raid10, you're probably better off with the SATA
raid10.

PostgreSQL doesn't have any kind of native clustering (depending on your
definition of clustering), but you might be able to roll your own
depending on your application.

I didn't know they were even making 300GB SCSI drives...

> Unfortunatly the Controllers in the three SUN-Servers do not support
> 300 GByte SCSI-Drives, so I have to continue with the Raid-5 of 16x
> 76 GByte.
>
> Oh yes, I have started the PostgreSQL in 03/2000 with 7x 18 GByte and
> never had problems with Raid-5.
>
> Suggestions?
>
> Please note, that in the coming year, my PostgreSQL will increase to
> at least 900 GByte (text only) and the corresponding FileServer with
> original Documents and additional Infos from 1,6 TByte to 28 TByte.
>
> OK, I was thinking of a Server-Farm of small AMD64FX or Opteron 140
> with two 300 GByte SCSI-Drives in Hardware Raid-1, and then installing
> 6-8 Systems running in Cluster, but I have no experience in such
> systems...
>
> And the price will explode... (Hardware recommandations?)
>
> Are there any acceptable Tyan Opteron 140 Mainboards with SCSI Raid-5
> onboard?  -  It should work with Debian GNU/Linux Sarge(amd64).
>
> Oh yes, I have seeen that 300 GByte Drives are around 1200 Euro/drive.
> So a "simpel" server will eat up at least 4200 Euro.
>
> Any suggestions are welcome.
>
>
> Greetings
> Michelle
>
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--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461