From: Scott Marlowe <smarlowe@g2switchworks.com>
To: Alex Turner <armtuk@gmail.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Bad iostat numbers
Date: Mon, 04 Dec 2006 10:25:14 -0600
Message-ID: <1165249513.14565.329.camel@state.g2switchworks.com> (raw)
In-Reply-To: <33c6269f0612032317t9f0bc77n3ff791a5cd88fc80@mail.gmail.com>
References: <PEEPKDFEHHEMKBBFPOOKKEHCDKAA.carlos.reimer@opendb.com.br>
<Pine.GSO.4.64.0612032336250.19679@westnet.com>
<33c6269f0612032317t9f0bc77n3ff791a5cd88fc80@mail.gmail.com>
On Mon, 2006-12-04 at 01:17, Alex Turner wrote:
> People recommend LSI MegaRAID controllers on here regularly, but I
> have found that they do not work that well. I have bonnie++ numbers
> that show the controller is not performing anywhere near the disk's
> saturation level in a simple RAID 1 on RedHat Linux EL4 on two
> seperate machines provided by two different hosting companies. In one
> case I asked them to replace the card, and the numbers got a bit
> better, but still not optimal.
>
> LSI MegaRAID has proved to be a bit of a disapointment. I have seen
> better numbers from the HP SmartArray 6i, and from 3ware cards with
> 7200RPM SATA drives.
>
> for the output: http://www.infoconinc.com/test/bonnie++.html (the
> first line is a six drive RAID 10 on a 3ware 9500S, the next three are
> all RAID 1s on LSI MegaRAID controllers, verified by lspci).
Wait, you're comparing a MegaRAID running a RAID 1 against another
controller running a 6 disk RAID10? That's hardly fair.
My experience with the LSI was that with the 1.18 series drivers, they
were slow but stable.
With the version 2.x drivers, I found that the performance was very good
with RAID-5 and fair with RAID-1 and that layered RAID was not any
better than unlayered (i.e. layering RAID0 over RAID1 resulted in basic
RAID-1 performance).
OTOH, with the choice at my last place of employment being LSI or
Adaptec, LSI was a much better choice. :)
I'd ask which LSI megaraid you've tested, and what driver was used.
Does RHEL4 have the megaraid 2 driver?
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To: pgsql-performance@postgresql.org
Cc: smarlowe@g2switchworks.com, armtuk@gmail.com, gsmith@gregsmith.com
Subject: Re: Bad iostat numbers
In-Reply-To: <1165249513.14565.329.camel@state.g2switchworks.com>
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