From: Joseph Marton (jmmarton_at_gmail.com)
Date: Sat Aug 04 2007 - 18:30:00 CEST
Message-ID: <859ece290708040930r440340bbv48fb935c19c54171@mail.gmail.com> Date: Sat, 4 Aug 2007 11:30:00 -0500 From: "Joseph Marton" <jmmarton@gmail.com> Subject: Re: [suse-sles-e] Slow direct I/O performance SLES 10 SP1
I'm not very familiar with IBM hardware, but looking at their site it
appears the 8k-I controller can only do RAID 0, 1, and 10. Since it
can't do 5 or 6 I can't help but to wonder if it doesn't have a
battery-backed write cache. If it doesn't, write performance is
probably going to be pretty poor. I'm guessing to get good
performance you'll need the straight 8k controller.
http://www-03.ibm.com/servers/eserver/xseries/cog/x3650/x3650io.html
"All x3650 models ship standard with ServeRAID-8k-l
which offers RAID 0, 1, 10. To upgrade to RAID 1E, 5
or 6, replace ServeRAID-8k-l with optional ServeRAID-8k,
pn 25R8064."
Joe
On 8/4/07, Andreas Mock <andreas.mock@web.de> wrote:
> Hi all,
>
> I've a little problem here and want to ask you if you could help me.
>
> I do have the following hardware at the moment:
> - IBM x3550 / x3650 x86_64
> - ServeRAID 8k-l SAS Controller, 2 SAS drives attached (aacraid-driver)
> - trying SLES 10 SP1 64bit
>
> When I do the following command on a local disk to check direct I/O
> performance without any load I only get about 1MB/sec. I'm pretty sure
> that's not too good and I don't understand why it is. As this is only a
> guess of me I wanted to get sure that this is not really normal.
>
> So I would like to ask you out there to do the same test and give some
> figures back.
>
> dd oflag=direct if=/dev/zero of=data.out bs=4k count=500000
>
> Please perform this test even when the hardware is not too similar.
> I would be also interested if this is a problem of 64bit vs. 32bit.
>
> Thank you in advance
> Andreas Mock
>
>
>
>
>
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