Unresponsive system during disk writes

[Mattias Sandgren]

Hello,

I've got an Adaptec 2940UW and and a Quantum Fireball 4.3GB U-SCSI drive.
There is something strange with the disk: doing large, long duration writes
to the disk makes my system grind to a halt until the transfers are done. The
mouse and keyboard are useless and X won't update.

Typically I use bonnie but high speed ftp/nfs (MBit speeds) induces the problem
as well.

The machine is a dual PII Mendocino at 450MHz with 128 MB memory. I've tried a
lot of kernel versions (most 2.2.x and some 2.3.x) with the stock aic7xxx
driver and the problem is there.  Different block-sizes and inode-counts on the
partitions, any kernel and aic7xxx driver, little or a lot of memory - it
doesn't matter.  I've tried fiddeling with different command queue lenghts as
well - to no avail.
The BIOS is 1.34.3 which I believe is the most recent. The card was purchased
in late 1996.

I recently purchased two IBM Ultrastar disks (LVD but using them as UW) and
started experimenting a little. The first thing I did was adding two swap
partitions on the new drives and stopped using the swap partition on the
Fireball. Result: The system felt a lot more responsive. Of course the
Ultrastar disks are fast but the main benefit was that the mouse pointer and
the keyboard was usable again when swapping takes place.

Next thing I did was create one large stripe using one partition from each
Ultrastar disk. The first thing I did was executing a bonnie run. And it went
so WELL. X didn't freeze and I could easily use the system while bonnie was
running despite having the swap partitions on the same two drives.

What is the problem with the Fireball disk?!
Is there some problem in combining the disk with the controller?
What can be done about it?

I've tried several ATA disks as well and they don't exhibit any problems
either. The system remains usable with them.

Follow this link to see logs and output (lspci, proc, log, bonnie etc):
http://leif.silicon.nu/mattias/diskproblem/


Regards
 Mattias


-- 
Mattias Sandgren - mailto:sagge at acc.umu.se http://www.acc.umu.se/~sagge
Computer Science and Engineering Student - University of Umea, Sweden.
One of them unix geeks. (  ( ( (( In Stereo Where Available )) ) )  )



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