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1996-11-14
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IOTEST 1.2 - Disk I/O Reliability Test
Copyright 1995 PowerQuest Corporation
All Rights Reserved
PowerQuest Corporation
1083 N State
Orem, UT 84057
voice: 801-226-8977
fax: 801-226-8941
email: scotl@powerquest.com
Web: http://www.powerquest.com
***** PLEASE READ THIS VERY CAREFULLY!! *****
IF YOU DO NOT, IT COULD COST YOU YOUR DATA. ALL OF YOUR FILES
ON ALL OF YOUR DRIVES COULD BE DESTROYED BY A DATA-CORRUPTING I/O ERROR!
We have found a serious data corruption bug in the PCI controller chip of many
popular computers. It shows up most easily when multitasking between the hard
drive and the floppy, but can be caused by other types of interrupts. The
corruption is a "loss" of bytes, causing all data after the lost bytes to
be shifted.
This has serious implications, and has destroyed partitions. If the operating
system happens to be reading the FAT when corruption occurs, the entire
partition can be destroyed. The PC-Tech RZ1000 chip is known to have this
problem.
We have found a work-around for some BIOSes: Changing the "PCI IDE prefetch
buffers" BIOS setting to DISABLED completely eliminates the error.
Unfortunately, not all machines with the problem allow this setting to be
changed by the user. Testing has shown that having the prefetch buffer on
gives a 2-3% performance boost.
IBM has developed a new disk driver to prevent this problem from occurring in
OS/2. It will detect the RZ1000 chip and disable PCI Prefetch Buffers if it
is present. It will be available on our web page (HTTP://WWW.POWERQUEST.COM)
on the week of August 14th.
The IBM OS/2 APAR number for this problem is PJ-19409.
HOW TO USE IOTEST
FOLLOW THESE INSTRUCTIONS VERY CAREFULLY
Usage: IOTEST <Test Drive Letter>
IOTEST will create a large file on the drive you specify. This file will have
a unique pattern that will show any read errors immediately. It also
continuously reads the disk, heavily exercising the disk I/O system. After
creating this test file, you will be instructed to begin formatting a floppy
or copying large files to a floppy. If your machine has the bug, ANY WRITE
OPERATIONS TO ANY PARTITION WHILE THE FLOPPY IS BEING FORMATTED COULD CAUSE
THE ENTIRE PARTITION TO BE DESTROYED. THIS INCLUDES THE OS/2 SWAPPER.DAT
FILE. DO NOT DO ANYTHING ELSE WITH YOUR COMPUTER WHILE RUNNING THIS TEST!
We recommend that you run the test on partitions that contain no valuable
data. If you do not have a partition to spare on a drive you wish to test, use
PartitionMagic from DOS to shrink your existing partitions and create some
free space. Then use FDISK to create a new partition that uses the newly
created free space. The test partition should be at least 5 MEG.
The test can be allowed to run for any period of time, but usually the amount
of time it takes to format two floppies is sufficient. All physical drives
should be tested.
EXAMPLE
IOTEST G:
HOW TO TEST WITHOUT IOTEST
1) Make a temporary directory.
2) Copy a number of files from one directory to the temporary directory.
3) Begin formatting a floppy in the background.
4) Use the operating system's file compare utility to compare the files
in the temp directory to the files in the source directory. For example:
OS/2: comp c:\os2\boot\*.* c:\temp\*.*
DOS: fc c:\dos\*.* c:\temp\*.*
5) This test should be run several times.
LICENSE
IOTEST may be distributed and used freely, provided that this README file
and IOTEST.EXE are kept together, and neither are modified.
Please give IOTEST to all your friends and colleagues, and post it on all BBS,
usegroups, and electronic forums that you frequent.