Who does this apply to?

Anyone using Windows 95 in a network using a Windows 95/Windows NT File Server.

This applies to ANY VERSION of Solution System 2 or CaseBASE for DATIS.

Issues Covered

• Windows 95 / Windows NT buffering problem. Provided is Microsoft's new version of VREDIR.VXD eliminates potential network problem.

Windows 95 / Windows NT buffering Problem

ACSL has been dealing with a situation where Windows 95 workstations that open files shared from Windows NT machines have problems with buffering.  Microsoft has now provided us with a new VREDIR.VXD for Windows 95 that does disable the buffering of files shared on Windows NT. The redirector executable is a self installing program provided by Microsoft. Run it under Windows 95 and it installs itself and makes the needed changes to your Windows registry. You then need to restart Windows 95 for the changes to take affect.   This applies to both OSR1 and OSR2. 

This new redirector removes the local caching that the old redirector automatically included. The local caching would cause data errors when retrieving data from an NT server. The new redirector has been extensively tested by Data Access Corporation and does indeed solve the problems with data reliability between a Windows 95 workstation and an NT server. This redirector is not needed if accessing data on a Netware server, however, installing the new redirector will have no detrimental affects on sites not using NT servers. Thus, our general recommendation would be to use the new redirector at all customer sites.

Go here to download this fix: http://www.acsl.com/support/vrdr2upd.exe

An important note: The new OSR2 version of Windows 95 (generally shipped with new machines in the last quarter of 1996 and into 1997), comes pre-installed with the new redirector. This is the same version of Windows 95 with the new FAT32 file system. However, OSR2 does not install with the necessary registry modifications, so it is still necessary to install the version of VREDIR.VXD or, make the registry changes described below:

Even if your machine came with the new VREDIR.VXD (Version 4.00.955) installed, you will still experience corruption problems if the registry key "DiscardCacheOnOpen" is not set to true (1 hex). This key is not defined as part of standard Windows 95 installations, but will automatically be defined and set if you use the patch provided to us by Microsoft.

You may verify (and correct, if necessary) this setting with Regedit by querying this key in HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services/VxD/VREDIR "DiscardCacheOnOpen" = (1 hex).

If you have OSR2 and you don't apply the patch, you can make the registry changes yourself:

Run the program Regedit.exe

Choose: HKey_Local_Machine ->
System ->
Current Control Set ->
Services ->
VxD ->
VREDIR ->
Right-Click or pull down "Edit" ->
New ->
Binary Value ->
Rename Value ->
Value name: DiscardCacheOnOpen
Modify ->
Parameter value: 00 01

Sharing CaseBASE Data Files on Windows NT Servers

You will experience data and index file corruption (or at least an apparent lack of synchronization between the data at various workstations) when using CaseBASE in configurations where the shared files are stored on a Windows NT Server. It was also reported that Microsoft Access had similar problems and required that opportunistic locking (an NT feature) needed to be disabled at the server for the Access application to function correctly. After examining the Microsoft Knowledge Base article Q129202 (Explanation of Opportunistic Locking on Windows NT), we re-tested CaseBASE and Solution System 2 after turning off the NT Server parameters for opportunistic locking. These settings, and how to change them, are shown in Opportunistic Locking and RFCB Caching in Windows NT Server 3.51 or Higher.

If you examine the Knowledge Base article, you will notice references to NT Workstation settings as well as the server settings. Our testing is limited to turning off OpLocks at the server. We have not tested the results of turning off OpLocks at all NT Workstations running CaseBASE and keeping it enabled at the server. It is possible that NT Workstation enforcement will also work, but our recommended and supported solution is to disable this feature at the server.

It is important to note that the updated VREDIR.VXD workstation fix is also required for stable operations when using Windows 95 workstations. There are actually two different operating-system-level functions at work when using combinations of Windows 95 and Windows NT workstations and Windows NT server: local buffering of data at the Windows 95 workstations (controlled by VREDIR.VXD and its registry settings at the workstation) and opportunistic-locking buffering at the Windows NT workstations (controlled by combinations of settings at the workstation and server, but only supported by disabling it at the server).