Re: How to allocate 8 disks - Mailing list pgsql-performance

From Joshua D. Drake
Subject Re: How to allocate 8 disks
Date
Msg-id 20080301130347.0832b323@commandprompt.com
Whole thread Raw
In response to How to allocate 8 disks  (Craig James <craig_james@emolecules.com>)
Responses Re: How to allocate 8 disks
Re: How to allocate 8 disks
List pgsql-performance
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On Sat, 01 Mar 2008 10:06:54 -0800
Craig James <craig_james@emolecules.com> wrote:

> We're upgrading to a medium-sized server, a Dell PowerEdge 2950,
> dual-quad CPU's and 8 GB memory.  This box can hold at most 8 disks
> (10K SCSI 2.5" 146 GB drives) and has Dell's Perc 6/i RAID controller.
> 
> I'm thinking of this:
> 
>   6 disks  RAID 1+0  Postgres data
>   1 disk   WAL
>   1 disk   Linux
> 
> I've often seen RAID 1 recommended for the WAL.  Is that strictly for
> reliability, or is there a performance advantage to RAID 1 for the
> WAL?
> 
> It seems to me separating the OS and WAL on two disks is better than
> making a single RAID 1 and sharing it, from a performance point of
> view.

This scares me... You lose WAL you are a goner. Combine your OS and
WAL into a RAID 1.

Sincerely,

Joshua D. Drake


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