perc 3/Di also unstable on 2.6.16.1 and tuned aacraid-1.1-5

Eric Sisler esisler at westminster.lib.co.us
Wed Apr 5 08:56:00 CDT 2006


On Wed, 2006-04-05 at 13:07 +0200, Ingvar Hagelund wrote:

> This may be like whipping a dead horse,

Pretty much.  ;-)

> but we gave one of our 2650 with
> Perc 3/Di a new go with linux-2.6.16.1 from kernel.org and aacraid
> driver 1.1-5 extracted from adaptec's latest rpm, and tuned
> AAC_MAX_32BIT_SGBCOUNT down to 256 in aacraid.h. We're also running
> latest firmware updates.
> 
> This worked quite good for a couple of hours. Then we made a new 20GB
> logical volume and ran fsck -t ext3 on it. It died as earlier by putting
> the controller offline. To regain control over the device we had to use
> the "normal" procedure, that is;

[snip]

> Will it ever be possible to run 2.6 stable with this controller?

I've given up on the PERC 3x line of cards entirely.

> Will software-raid (md) work stable?

It *should*, see below.

> Eric Sisler posted in January under the subject "Two more reasons to
> avoid the PERC 3/Di RAID card (GRUB & fsck)" that it was possible to
> bypass the Dell firmware, "effectively turning the card into an Adaptec
> AIC-7899 dual-channel SCSI card". Is this a trivial task? Will it work
> with existing raid sets?

Turning the RAID functionality off is pretty easy - you can do so in the
BIOS (I forget exactly where).  You can also open the chassis and remove
the RAID key, cache memory and battery to prevent accidental re-enabling
of RAID functionality if you want.

This will NOT preserve any existing hardware RAID containers/data, so
make sure you backup your data first.  In effect you are replacing one
hardware component with another, completely different one.

The AIC-7xxx driver for Linux has been around for quite some time, so
software RAID should be stable.  I found it slightly faster than
hardware RAID during my testing.

I wound up replacing the card with a PERC 4/DC, which is LSI based and
uses the megaraid driver.  If you don't have the split backplane you
should be able to use a PERC 4/SC.  Someone mentioned writing a quick
script to hammer away on the array by creating a large file using dd,
deleting the file, repeat.  I wrote a script and ran two instances of it
on and off for ~2 weeks and the server remained solid.

Another little tidbit about the PERC 3/Di - it's actually only Ultra160
SCSI.  If you have Ultra320 drives in the chassis, you should see some
performance gain by switching to a PERC 4/x card, which is Ultra320.
You'll need to make sure the drive backplane is U320, according to Dell
2650's with the upgraded backplane began shipping December 2003.  Beats
me why Dell would sell customers U320 drives connected to a U160 RAID
card.

-Eric

-- 
Eric Sisler <esisler at westminster.lib.co.us>
Library Applications Specialist
Westminster Public Library
Westminster, CO USA

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