RE: Raid 50
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 6 Jul 2004 17:05:53 -0400
Basically it means that it takes no more than 3 drive failures per 21 disk
set to actually fail the array (configurations may vary) as opposed to 2 of
5 for raid 5 or 2 of 2 for raid 1. I don't know whether this is an
officially recognized RAID nomenclature, and I believe it is a marketing
attempt to convince people that the i/o pitfalls of raid 5 can be somewhat
ameliorated by using more disks "simultaneously." I'm not talking about
continuing operations in "damaged" mode, I'm talking about failing. As with
raid 5, any single disk failure will incur parity reconstruction of some
type for the affected raid, so by typically ganging together more disks per
raid group, your chances of running in "damaged" mode increases.
I must admit that I have not tested it, since just based on the description
I concluded that it had all the significant potential performance problems
of raid 5 combined with increased risk.
I would love to hear performance data on using raid 50 with Oracle,
especially if the i/o profile included the knee curve when you approach
steady state cache overrun, and at what generation rate of redo logs or some
other transaction metric you reach the knee curve. If someone supplies this,
please note your array configuration, since I think "RAID 50" specifications
vary considerably.
Google of "RAID 50" will get you quite a few sites. Apparently it is a
pretty big hit for static gaming data.
(Short answer: Ever seen Monty Python and the Holy Grail? Make like Brave
Sir Robin, but try not to rust your armor while running away!)
mwf
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of David
Sent: Tuesday, July 06, 2004 1:40 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Raid 50
I am well aware of the pros and cons of RAID 0, 1, 0+1, 1+0(raid 10), 5,
etc.
But, here is a new one on me...RAID 50.
Thoughts, experience...please elaborate asI just found out it's our RAC IO
backend.
--
..
David
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