Data Corruption with Microsoft Windows 95 Operating System Release 2 and FAT32

Article ID: accp511

The information in this article applies to the ACCPAC Plus for DOS Windowing System Manager.

Problem

Some clients have reported data corruption in their ACCPAC Plus data files when using Windows 95 Operating System Release 2 (OSR2) with FAT 32 as a workstation on a Microsoft network. Our initial test on a Windows 95 with FAT32 peer-to-peer network confirmed the data corruption. Our initial advice to clients was to reformat their hard drive to FAT16. In some cases they had to reinstall Win95 OSR1 before the problem disappeared.

Windows 95, like Windows NT has the ability to cache shared records locally. The problem occurs when two workstations are sharing the same record. The first workstation updates the record in local cache. This update is not written to the hard drive immediately. Meanwhile, the second workstation, unaware that the record was updated, updates the record in its local cache. When both workstations write the updated record to the hard drive, data corruption occurs. There is a similar problem with opportunistic locking in Windows NT, but unlike Windows NT, caching cannot be turned off in Windows 95.

Resolution

We discussed this problem with Microsoft and downloaded a fix to the network redirector, Vredir.vxd. We have tested this fix on a Windows 95 OSR2 with FAT32 peer-to-peer network and found that the problem disappears. This fix, article Q148367, can be found on the Microsoft Knowledge Base on the Internet at http://support.microsoft.com/support/kb/articles/Q148/3/67.asp. It requires you to download the file, VRDRUPD.EXE. This file will update the following files, Vredir.vxd and Vnetsup.vxd, in your Windows/System directory. We suggest that you update each Windows 95 (OSR2) workstation on your network.

This information has been provided by ACCPAC International, Inc.

Last Modified:  March 19, 2004