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Re: Three drive raid set.



fixed

Well the numbers here do make sense. That is drive 52 with twice the capacity is getting twice the work to do as drives 54 and 55. I would strongly recommend against any use of three drive raid sets in a production environment for this reason. Given there are 55 drives (at least) in the system, there must be some other drives (#51 appears a candidate already) that could be moved to this raid set to allow it to be rebuilt as a 4 drive set. *caution* your data is exposed during that rebuild because the only way to get Parity spread across 4 drives is to stop and re-start raid.

 - Larry

rob@xxxxxxxxx wrote:

Anyone else out there have serious performance issues with a three drive raid set? We are. And we even ran STRASPBAL. IBM tried iDoctor, etc. Nothing out of the ordinary. So, their suggestion is a STRASPBAL *ENDALC and then add them back in with STRASPBAL *CAPACITY.

Our BP says he knows of another customer that had the same issue but just ordered another drive and it was solved. Never opened pmr with IBM.

Trying to find a few "me too's", hopefully with pmr #'s, to encourage IBM to look harder.

We will buy more drives. We were hoping to put it off awhile. Boss does think that getting them in before year end is a good thing though, budgetwise.

System ASP . . . . . . . :     3316 G
% system ASP used  . . . :    74.9333

WRKDSKSTS
Size % I/O Request Read Write
Unit Type (M) Used Rqs Size (K) Rqs Rqs ...
50 4327 52923 74.9 15.3 8.6 7.0 8.2
51 4327 70564 74.9 25.3 7.9 13.7 11.6
52 4327 61744 74.9 29.4 6.4 17.7 11.6
53 4327 70564 74.9 131.3 5.9 47.3 83.9
54 4327 35282 74.9 50.7 6.6 13.8 36.8
55 4327 35282 74.9 70.0 5.6 22.0 47.9


The last three are the raid set in question.

Rob Berendt



--
Larry Bolhuis IBM eServer Certified Systems Expert:
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