Unexplained I/O errors

Tue Jul 17 08:41:31 PDT 2001

We had similar problems with UDMA and the 2.4.X kernels
on this particular type of MB. You could try setting
/sbin/hdparm -c1 -d1 -X32 /dev/hda

You can also try running a kernel without any UDMA
support compiled in.

A third option is to compile the kernel without initial
UDMA support.

A fourth possibility is that one of your hardware components is
really broken ;-)

Good luck,
Matthijs
____________________________
Dr ir Matthijs van Leeuwen
HPC Specialist
Compusys Plc, 58 Edison Road
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Aylesbury, Bucks HP19 8UT, UK
Tel: +44 (0)1296 505143
Fax: +44 (0)1296 424165
Email: m.vanleeuwen at compusys.co.uk
Web: http://www.compusys.co.uk

-----Original Message-----
From: Steven Timm [mailto:timm at fnal.gov]
Sent: Tuesday, July 17, 2001 4:19 PM
To: beowulf at beowulf.org
Subject: Unexplained I/O errors

Hi everyone,

We are currently burning in a new cluster and seeing the following
problem:

We see a number of files, usually contiguous in the same directory,
that ls will list as being there, but ls -l will show Input/output error.
An fsck of the system gets rid of the I/O errors but also gets
rid of the file.  There is no error message on the console, nor
in /var/log/messages, to indicate any disk controller problems.

The problem appears to get worse over time, over a period of a few
days the majority of our 136 machines exhibit these errors.

Our configuration:  Supermicro 370DLE motherboard, 2x1000MHz pentium III,
512 MB ram, Seagate system disk (30 GB)  and CDROM on IDE primary,
2x40GB IBM drives on IDE secondary.
hda: ST330620A, ATA DISK drive
hdb: CD-ROM 48X/AKH, ATAPI CDROM drive
hdc: IC35L040AVER07-0, ATA DISK drive
hdd: IC35L040AVER07-0, ATA DISK drive

I/O errors happen only on the system disk.

We swapped out a large number of IDE cables for the system disk,
replacing them with a better grade, with no luck.

We have downgraded a few machines to the 2.2.16 kernel, and this
appears to be OK, but it is a bit early to tell.

We have also pulled the CD roms off of a few machines and this
also appears to be stable but we need more data yet.

Any idea what could be causing all of this?

Steve

------------------------------------------------------------------
Steven C. Timm (630) 840-8525  timm at fnal.gov  http://home.fnal.gov/~timm/
Fermilab Computing Division/Operating Systems Support
Scientific Computing Support Group--Computing Farms Operations

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