Re: RAID -v- Mirroring (was New RAID-5 algorithm on V4R5 ?)

[Larry Bolhuis <lbolhuis@xxxxxxxxxx>]

Charly,

  Do you feel that this is the primary point where mirroring out-runs
RAID?  In other words given equal speed controllers and disks of
identical total protected size, assuming cache is not overrun, which
will perform better doing writes?  By how much?

  Why would Mirroring not be in the same trouble if write cache is
overrun? Or is it just that w/ mirroring it is more difficult to overrun
it?

 - Larry

> ok.  I'll respond.  If you insist.  When you are in a write intensive
> environment, and you overrun your write cache, the performance of
> mirrored disks is significantly better than RAID disks.  You may not
> think you would ever have this problem, but how would you know even
> if you did?  I have seen this situation with journal receivers on
> systems where they were journalling a lot of stuff.

-- 
Larry Bolhuis
Arbor Solutions, Inc.
(616) 451-2500
(616) 451-2571 -fax
lbolhuis@arbsol.com
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