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Re: Is Raid 5 really that bad for Oracle?

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Tue, 03 Aug 2004 20:15:43 +0800
Message-ID: <410F81EF.533A@yahoo.com>


Niall Litchfield wrote:
>
> "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

True story...

Company X moving from JBOD to SAN. JBOD totals around 800G so the SAN is populated to 800G as well...Of course, in the JBOD, each 18G disk ends up being around 17.5G available to the OS. In the SAN, each 36G disk ends up being around 30G to the OS

Result:
- They've halved the number of spindles
- They've not enough disk space
but hey...at least we've got a SAN

:-)

-- 
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
ISBN: 1590592174

web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com

Coming Soon! "Oracle Insight - Tales of the OakTable"

"GIVE a man a fish and he will eat for a day. But TEACH him how to fish,
and...he will sit in a boat and drink beer all day"

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Received on Tue Aug 03 2004 - 07:15:43 CDT

Original text of this message

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