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Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)

To: b.j.smith@xxxxxxxx
Subject: Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)
From: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>
Date: Tue, 25 Sep 2007 19:38:55 -0400 (EDT)
Cc: Ralf Gross <Ralf-Lists@xxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <498689.78850.qm@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
References: <498689.78850.qm@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx


On Tue, 25 Sep 2007, Bryan J. Smith wrote:

Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote:
Just out of curisosity have you tried SW RAID5 on this array?
Also what do you get if you use RAID0 (hw or sw)?

According to him, if I read it correclty, it is an external FC RAID-5
chassis.  I.e., all of the logic is in the chassis.  So your question
is N/A.

Although I'm more than ready to be proven incorrect.

Furthermore, what benchmark do you use?  If dd on the volume itself,
software RAID wins, hands down.  Doesn't matter what size you give
it, it literally copies (and doesn't recalculate) the parity.  It's
the rawest form of non-blocking I/O, and uses virtually no system
interconnect to the CPU (just pushes disk-mem-disk).

--
Bryan J. Smith   Professional, Technical Annoyance
b.j.smith@xxxxxxxx    http://thebs413.blogspot.com
--------------------------------------------------
    Fission Power:  An Inconvenient Solution


bonnie++, iozone, etc..

all show ~430-460 MiB/s write and ~550 MiB/s read

Justin.


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