Re: Bad iostat numbers

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?