BTW, tnx for the opinion ...
I forgot to cc list ...


Begin forwarded message:

From: Yves Vindevogel <[EMAIL PROTECTED]>
Date: Fri 17 Jun 2005 23:29:32 CEST
To: [EMAIL PROTECTED]
Subject: Re: [PERFORM] Multiple disks: RAID 5 or PG Cluster

Ok, striping is a good option ...

I'll tell you why I don't care about dataloss

1) The database will run 6 months, no more.
2) The database is fed with upload files. So, if I have a backup each day, plus my files of that day, I can restore pretty quickly.
3) Power failure is out of the question: battery backup (UPS), disk failure is minimal change: new server, new discs, 6 months ...

We do have about 500.000 new records each day in that database, so that's why I want performance
Records are uploaded in one major table and then denormalised into several others.

But, I would like to hear somebody about the clustering method. Isn't that much used ?
Or isn't it used in a single machine ?

On 17 Jun 2005, at 22:38, [EMAIL PROTECTED] wrote:

If you truly do not care about data protection -- either from drive loss or from
sudden power failure, or anything else -- and just want to get the fastest
possible performance, then do RAID 0 (striping). It may be faster to do that
with software RAID on the host than with a special RAID controller. And turn
off fsyncing the write ahead log in postgresql.conf (fsync = false).

But be prepared to replace your whole database from scratch (or backup or
whatever) if you lose a single hard drive. And if you have a sudden power loss
or other type of unclean system shutdown (kernel panic or something) then your
data integrity will be at risk as well.

To squeeze evena little bit more performance, put your operating system, swap
and PostgreSQL binaries on a cheap IDE or SATA drive--and only your data on the
5 striped SCSI drives.

I do not know what clustering would do for you. But striping will provide a
high level of assurance that each of your hard drives will process equivalent
amounts of IO operations.

Quoting Yves Vindevogel <[EMAIL PROTECTED]>:

Hi,

We are looking to build a new machine for a big PG database.
We were wondering if a machine with 5 scsi-disks would perform better
if we use a hardware raid 5 controller or if we would go for the
clustering in PG.
If we cluster in PG, do we have redundancy on the data like in a RAID 5
?

First concern is performance, not redundancy (we can do that a
different way because all data comes from upload files)

Met vriendelijke groeten,
Bien à vous,
Kind regards,

Yves Vindevogel
Implements





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Met vriendelijke groeten,
Bien à vous,
Kind regards,

Yves Vindevogel
Implements

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Met vriendelijke groeten,
Bien à vous,
Kind regards,

Yves Vindevogel
Implements

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Mail: [EMAIL PROTECTED] - Mobile: +32 (478) 80 82 91

Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76

Web: http://www.implements.be
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