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 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.