Re: Oracle & I/O Performance

From: Uwe Schneider <pi_at_richard-schneider.de>
Date: Wed, 13 Oct 1999 21:33:28 +0000
Message-ID: <3804FAA8.4B295AA3@richard-schneider.de>

Hi Robert,

Robert Luscombe wrote:
>
> I was wodering what advice anyone can offer some advice regarding I/O
> performance and hardware RAID.
>
> I am setting up Oracle under Solaris using a couple Sun disk arrays with
> hardware RAID. Has anyone found that it is better to isolate
> high-activity tables in their own tablespaces on several separate disk
> groups, or will performance likely be better using fewer disk groups
> with more disks in each group? Will I likely see better I/O by keeping
> these tables physically separate by putting them each on smaller disk
> groups (such as four groups of six disks, one tablespace per group) or
> putting all of them on fewer large disk groups (such as one group of 24
> disks or 2 groups of 12)?

I think the principal rule is to use as many logical disks as possible, since then the sum of the DB activities requires the least number of waits for "head" positioning. (A RAID behaves like one logical disk with one locgical read/write head.)

In my experience availability has priority no. 1, therefore you use RAID. Second is performance. This means, that you should use as many RAID groups as you can afford within your technical and financial boundaries (larger RAID groups have less redundancy, thus are cheaper concerning space/cost).

Regards!
--

Uwe Schneider       | Telefon +49 7251 / 82587
Karlsdorfer Str. 31 | Mail    pi_at_richard-schneider.de
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Linux - OS al dente! Received on Wed Oct 13 1999 - 16:33:28 CDT