Re: Is Raid 5 really that bad for Oracle?

From: Niall Litchfield <niall.litchfield_at_dial.pipex.com>
Date: 3 Aug 2004 04:51:30 -0700
Message-ID: <b6beca79.0408030351.7211236f@posting.google.com>

"Cary Millsap" <cary.millsap .at. hotsos .dot. com> wrote in message news:<10gu902j8cmcs7b_at_corp.supernews.com>...
> 2. But mirroring is expensive per byte of storage. Hence RAID levels 2, 3,
> 4, 5, and 6 were proposed. Their design goals were to lessen the
> expense-per-byte of storage of RAID level 1 (mirroring). For example, with
> G=5 RAID level 5, the price of resilience per byte of storage is 5/4 of a
> 4-disk array instead of 8/4.

I meant to make a similar point originally, but didn't. Namely that RAID5 tends to make sense from a COST/GB point of view and SAME tends to make sense from a COST/IO point of view. Often these two views are where the disagreement lies. If my sysadmins ask me how much storage I want, they do not want to be told (say) 100gb and 2500 IO/sec. They just want the former figure.

Niall Received on Tue Aug 03 2004 - 06:51:30 CDT