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utilizing multiple disks for i/o performance
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* utilizing multiple disks for i/o performance
@ 2006-05-20 02:37 Kenji Morishige <kenjim@juniper.net>
  2006-05-22 15:14 ` Re: utilizing multiple disks for i/o performance Scott Marlowe <smarlowe@g2switchworks.com>
  2006-05-22 15:21 ` Re: utilizing multiple disks for i/o performance Jim C. Nasby <jnasby@pervasive.com>
  0 siblings, 2 replies; 3+ messages in thread

From: Kenji Morishige @ 2006-05-20 02:37 UTC (permalink / raw)
  To: pgsql-performance; +Cc: kenjim@juniper.net

Where can I find any documentation to partition the tablespace disk files onto
different physical arrays for improved performance?

-Kenji



^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: utilizing multiple disks for i/o performance
  2006-05-20 02:37 utilizing multiple disks for i/o performance Kenji Morishige <kenjim@juniper.net>
@ 2006-05-22 15:14 ` Scott Marlowe <smarlowe@g2switchworks.com>
  1 sibling, 0 replies; 3+ messages in thread

From: Scott Marlowe @ 2006-05-22 15:14 UTC (permalink / raw)
  To: Kenji Morishige <kenjim@juniper.net>; +Cc: pgsql-performance

On Fri, 2006-05-19 at 21:37, Kenji Morishige wrote:
> Where can I find any documentation to partition the tablespace disk files onto
> different physical arrays for improved performance?

There have been quite a few posts to this list in the past about this,
so searching it might be a good start.

Firstly, you need to defined "improved performance".  Are we talking
transactional throughput (OLTP), or batch updates (ETL), or report
generation (OLAP stuff)???  Or some other scenario.

For write performance, the general rules are:

You can only commit 1 transaction per rotation of a properly fsynced
disc that holds the WAL file (i.e. the pg_xlog directory).  So, putting
that on it's own fast spinning disc is step one for improved
performance.

A battery backed cache unit (BBU) on a RAID controller is a must.

RAID 1+0 is a good choice for your data partition.

For many hardware RAID controllers with the above mentioned BBU moving
the pg_xlog to another partition is no real help.

Cheap RAID controllers are often worse than no RAID controller.  If you
can't afford a good RAID controller, you're probably better off with
software RAID than using a cheapie.

For READ performance:

Often settings in postgresql.conf are far more important than the drive
layout.  

Lots of RAM is a good thing.

Assuming you've got lots of RAM, making shared_buffers anywhere from 10
to 25% of it is a pretty good size.

work_mem usually works well at around 16 meg or so.

drop random_page_cost to about 2 for most systems.

Lastly, read this:

http://www.varlena.com/GeneralBits/Tidbits/perf.html



^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: utilizing multiple disks for i/o performance
  2006-05-20 02:37 utilizing multiple disks for i/o performance Kenji Morishige <kenjim@juniper.net>
@ 2006-05-22 15:21 ` Jim C. Nasby <jnasby@pervasive.com>
  1 sibling, 0 replies; 3+ messages in thread

From: Jim C. Nasby @ 2006-05-22 15:21 UTC (permalink / raw)
  To: Kenji Morishige <kenjim@juniper.net>; +Cc: pgsql-performance

On Fri, May 19, 2006 at 07:37:45PM -0700, Kenji Morishige wrote:
> Where can I find any documentation to partition the tablespace disk files onto
> different physical arrays for improved performance?

Other than CREATE TABLESPACE??
-- 
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



^ permalink  raw  reply  [nested|flat] 3+ messages in thread


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2006-05-20 02:37 utilizing multiple disks for i/o performance Kenji Morishige <kenjim@juniper.net>
2006-05-22 15:14 ` Scott Marlowe <smarlowe@g2switchworks.com>
2006-05-22 15:21 ` Jim C. Nasby <jnasby@pervasive.com>

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