Message-Id: <972BDF1A-B4ED-46EC-B416-0CDF15A0439A@technocon.com>
From: Christiaan Willemsen <cwillemsen@technocon.com>
To: pgsql-performance@postgresql.org
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Subject: How to setup disk spindles for best performance
Date: Thu, 21 Aug 2008 00:25:59 +0200

I'm currently trying to find out what the best configuration is for  
our new database server. It will server a database of about 80 GB and  
growing fast. The new machine has plenty of memory (64GB) and 16 SAS  
disks, of wich two are already in use as a mirror for the OS.

The rest can be used for PostgreSQL. So that makes a total of 14 15k.5  
SAS diks. There is obviously a lot to interesting reading to be found,  
most of them stating that the transaction log should be put onto a  
separate disk spindle. You can also do this with the indexes. Since  
they will be updated a lot, I guess that might be a good idea. But  
what no-one states, is what performance these spindle should have in  
comparison to the data spindle? If I create a raid 10 of 6 disks for  
the data, 4 disk raid 10 for the log, and 4 disk raid 10 for the  
indexes, will this yield best performance? Or is it sufficient to just  
have a simple mirror for the log and/or indexes...? I have not found  
any information about these figures, and I guess it should be possible  
to give some pointers on how these different setup might affect  
performance?

So I hope someone has already tested this and can give some tips...

Kind regards,

Christiaan