DMATEST 1.0 - Dual-DMA Data-Transfer 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 ***** 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 DMA-TRANSFER BUG!! We have found a serious data-corruption bug when using dual-DMA transfer on some computers. It shows up when multitasking between the hard drive and another device such as a floppy drive or a network. When this happens, the data can get shifted by 2 or more bytes. This has serious implications, and has already destroyed many partitions. If the operating system happens to write to the hard drive at the same time that you access a another peripheral device (floppy, network, CD_ROM, etc.), the drive can become corrupted, and the entire partition destroyed. Every PCI EIDE system we have in house has this problem. We have found a work-around for some BIOSes: Changing the "PCI IDE prefetch buffers" BIOS setting to DISABLED prevents the error. Unfortunately, not all machines with the problem allow this setting to be changed by the user. HOW TO USE DMATEST FOLLOW THESE INSTRUCTIONS VERY CAREFULLY Usage: DMATEST DMATEST is an OS/2 text-mode program that will create a large file on the drive you specify. This file has a unique pattern that allows detection of any read errors. DMATEST continuously re-reads the file, ensuring that a dual-DMA transfer will be used if a peripheral device is accessed. 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 DMA bug, ANY WRITE OPERATIONS TO ANY PARTITION WHILE THE FLOPPY IS BEING ACCESSED COULD CAUSE THE ENTIRE PARTITION TO BE DESTROYED. DO NOT DO ANYTHING ELSE WITH YOUR COMPUTER WHILE RUNNING THIS TEST! All physical disks on the system should be tested. The partition that will contain the test file SHOULD HAVE NO VALUABLE DATA. If you do not have a partition to spare on a drive you wish to test, use PartitionMagic either from DOS or from OS/2 BOOTED FROM FLOPPIES 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. Each test partition should be at least 5 MEG. EXAMPLE CONFIGURATION: DISK 1: C: E: F: G: DISK 2: H: I: DISK 3: D: J: K: TO TEST ALL PHYSICAL DRIVES: DMATEST G: DMATEST I: DMATEST K: LICENSE DMATEST is Copyrighted by PowerQuest Corporation, the makers of Partition Magic DMATEST may be distributed and used freely, provided that this README file and DMATEST.EXE are kept together, and neither are modified. Please give DMATEST to all your friends and colleagues, and post it on all BBS, usegroups, and electronic forums that you frequent. If you find any new information about this DMA bug, please forward it to PowerQuest at the address listed above.