Redirector Problems and Other Network Problems

Last reviewed: 03/22/2010
Article ID: R10200

Summary

When application software is deployed on a network, any shortcomings or weaknesses in the operating system or network are inherited by the application. As a result, when network problems occur, they affect the application software. Because the problems appear to occur in the application software, frequently the application software is blamed. However, data corruption and problems that are manifested in the application software are quite often the fault of problematic networking software (and sometimes hardware issues). As the number of users increase, so does the network traffic and so can the frequency of any underlying problems. Because of the complexity of a networking system, when data corruption occurs, it can be very difficult to diagnose and troubleshoot problems, even for trained specialists. 

This document is a white paper that was written to educate our customers, resellers and other third parties about the various problems associated with networks and redirectors that we have encountered on a regular basis. This document also discusses diagnosis and treatment of these problems. 

Note: Software Technology, Inc. no longer supports Windows 95 since Microsoft has discontinued support of this operating system. However, many references to Windows 95 have been retained in the article for historical purposes.

Problems with Network Software

The following is a list of some of the issues that are discussed in this article:

• When lockup or corruption problems occur, it is important to verify that the most current server software, operating system software and network card drivers are installed. Although this is an easy concept in theory, in practice, it may not be so easy. This article will provide the necessary procedures and details for individuals who may not have the prerequisite background or experience in network administration.
• Users with Windows 2003/XP/2000 file servers may also experience intermittent lockups and possible data file corruption due to problems with Windows's opportunistic locking feature.
• Data corruption can occur on Novell platforms when some settings are optimized for performance because of a trade-off with reliability (i.e., TURBO FAT and opportunistic locking).

What is a Redirector?

The software that allows workstations or "clients" to "talk to" a server via a network is referred to as redirector software. Redirector software for networks is provided primarily by Microsoft and Novell. This software is an extremely critical component of any network. Each workstation on a network has its own redirector software. For example, if you have one workstation running Windows Vista and another workstation running Windows XP, each of these workstations has different redirector software. If there are "bugs" or "glitches" in the redirector software, it can cause all kinds of problems with other software programs.

Symptoms

In past years, we have had reports of problems with errors such as 1400-0-160-0 and 1400-0-69-0. Duplicate Key errors have been reported by our Data File Integrity Check (error 69) and Reindex Files programs. Other users have received intermittent lockups due to "Invalid Page Fault" errors.

Cause

Redirectors attempt to increase performance by caching parts of files in the memory of the local computer instead of getting the latest information from the network server. Unfortunately, the caching algorithms used have some problems that interfere with multi-user database programs such as Tabs3.

It is important to note that these data corruption problems are due to problems in Microsoft and Novell software components. They are not due to Tabs3 or PracticeMaster programs. Although the file access routines used in Tabs3 expose these problems, it is important to note that the corruption problems are not limited to our programs.

Solution

The solution to network or data corruption problems is a multi-pronged approach consisting of the following:

• Making sure all of your network servers AND clients have the most current Service Pack(s) installed. Failure to keep up with of the most current patches available for your network can result in unnecessary problems and expense.
• Implementing the specified registry settings in this document for all workstations on the network. Registry settings can be implemented manually or by using our Network Settings utility program.
• Disabling certain performance optimization features that affect reliability. Specifically, this includes:
• Disable Opportunistic Locking on any Windows 2003/XP/2000 servers.
• Disable Opportunistic Locking on any Novell servers.
• Making sure the most current drivers for your Network Interface Card have been installed.

CAUTION: Editing the Windows registry is typically not recommended because of potential problems that can occur when not done properly. We are not responsible for edits made to the registry. The recommended registry changes actually require the addition of values to subkeys and should not be attempted unless familiar with the registry. Any registry changes should be made by your network administrator or a qualified professional. Because of this recommendation, we have provided the recommended registry changes; however, we have not included step-by-step directions for implementing these changes. (Our Support personnel do not have the necessary training to help you with Windows registry changes.)

WARNING: The following disclaimer is used by Microsoft regarding editing of the registry: "Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk."

IMPORTANT: Microsoft recommends making a back up copy of the registry files before editing the registry. Refer to Microsoft documentation for details on how to back up the registry.

Network Settings Utility Program

The Network Settings utility program, included in all Tabs3 and PracticeMaster Software Version 15.3 and later, can be used to test for current network configuration on network workstations and most file servers. This program also tests for our recommended Windows registry settings including Windows 2008/Vista/2003/XP/2000 opportunistic locking settings and can be used to automatically implement those registry settings if they need to be changed (provided you have sufficient Windows rights and are logged in as a manager).

Additional information about the Network Settings program can be found in KB Article R11309, "Network Settings Technical Information".

Redirector Identification

A redirector is the part of the operating system that lets a computer talk to another computer. The other computer may be a Novell server or other Windows computer. There are several redirectors available for Windows:

• Client 32 Redirector
  Provided by Novell
  Used when connecting a Win XP/2000 computer to a NetWare server computer.
• Windows Redirector
  Provided by Microsoft
  Used when connecting a Win XP/2000 computer to a Windows computer.

Do I need to update redirectors for Windows Vista/XP/2000 clients?

Redirectors are updated differently for Windows Vista/XP/2000 clients. Instead of downloading and updating separate patches (as was the method for Windows 98/95), patches are included in a consolidated Service Pack. Therefore, for Windows Vista/XP/2000 clients, simply verify that the most current Service Pack has been installed. The most current Service Packs for Windows Vista/XP/2000 clients are the same as those listed in the Microsoft Server section of this document. 

Do I need to implement registry settings for Windows XP/2000 workstations?

Yes. Our Network Settings utility program can easily do this for you.

How can you tell which version of the Client 32 Redirector is being used?

Perform the following steps:

1. Right-click the "N" icon in the System Tray. (If using Windows XP, it is possible that this icon could be hidden. One way to show the icon is to click the circle icon with the arrow pointing to the left; this will expand the system tray icons to show hidden icons.)
2. Select Novell Client Properties.
3. On the Client tab, the Client Version and Service Pack that is installed will be displayed. If no version number is shown, the redirector being used is older than version 3.0.

Recommended Registry Settings and How to Download Current Redirectors

The following information includes technical information, recommended registry settings and how you can download the most current redirector from the Internet.

Note: The latest Microsoft redirectors are included with each service pack and are no longer available as separate downloads. Therefore, we recommend installing the most current Microsoft service packs as they become available for your operating system.

SERVER ISSUES 

It is important to make sure that the server being used has the latest Service Pack installed. The following lists the most current Service Packs for both Microsoft and Novell servers and also identifies issues known to cause data corruption.

Microsoft 2008/Vista/2003/XP/2000 Servers 

Make sure that the latest Service Pack is installed. As of this writing (October 2009), the latest versions of Windows servers are:

Note: Tabs3 and PracticeMaster will run under Windows Vista SP1. However, when running in a network environment on a server that is running under Vista with UAC enabled, our testing has shown that you may experience intermittent connection reliability issues. Although Vista SP1 significantly reduced the number of these issues, our testing did encounter connection issues with UAC enabled on the server.

To determine which Service Pack is installed on a Microsoft server:

• Right-click My Computer and select Properties. The Windows operating system, version and service pack will be shown.

Problems with Opportunistic Locking on 2003/XP/2000 Servers

Users can also experience file corruption due to the use of opportunistic locking by Windows. This is a problem that affects networks with Windows 2003/XP/2000 servers. Novell networks are not affected.

What is opportunistic locking?

Opportunistic Locking is another attempt at allowing computers on a network to cache data locally instead of retrieving data from the Windows 2003/XP/2000 server with the hope of improving performance. Again, there seem to be problems in at least some situations where opportunistic locking doesn't work quite right.

Opportunistic locking is explained in Microsoft Knowledge Base Article #129202, "Explanation of Opportunistic Locking on Windows NT". It is interesting to note that this article states:

"Oplocks are a significant performance enhancement, but have the potential to cause lost cached data on some networks ..."

Microsoft has acknowledged problems with Opportunistic Locking in Microsoft Knowledge Base Article #303528, "How to Keep a Jet 4.0 Database in Top Working Condition".

How is opportunistic locking disabled?

We recommend disabling opportunistic locking at the Windows 2003/XP/2000 Server in order to prevent data corruption. To do so, you can use our Network Settings utility program on a Windows 2003/XP/2000 Server or you can edit the Registry (on the 2003/XP/2000 server).

HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services/LanmanServer/Parameters
          EnableOpLocks = 0 (hex)
          EnableOpLockForceClose = 1 (hex)
          CachedOpenLimit = 0 (hex)

Note: The above values should be added as DWORD values if not present.
Note: Opportunistic locking is configured by default with Windows 7/Vista and cannot be disabled when communicating with Windows Server 2008.

Novell NetWare Servers

Make sure that the latest Support Pack (SP) is installed. As of this writing (October 2009), the latest versions of NetWare servers are:

To determine which Support Pack is installed on a Novell server:

• From the System Console command prompt, type Version. The NetWare Server version and Support Pack will be shown.

Note: See KB Article R11262, "Statement on Novell NetWare Compatibility".

Problems with Opportunistic Locking on Novell NetWare Servers 

Novell NetWare also includes an Opportunistic Locking feature. We recommend that Opportunistic Locking be DISABLED at the Novell NetWare File Server. This applies to servers running under Version 5.0 SP5, Version 5.1 SP2, or later.

This setting can be disabled by:

• editing the AUTOEXEC.NCF file (system directory) or the STARTUP.NCF file (DOS partition); or 
• typing the command at the command line of the File Server. 

The command to disable the setting is the same regardless of which method is used to implement it. The command is:

SET CLIENT FILE CACHING ENABLED = OFF

We recommend editing the AUTOEXEC.NCF file, which requires rebooting the server after adding the command. However, the command line method can be used temporarily until it is more convenient to reboot the server.

Network Interface Card Issues

Network Interface Card Drivers

Always make sure the latest Network Interface Card (NIC) driver is being used. Current drivers are typically available from the manufacturer of your NIC card.

Power Management

NICs can be configured with their own set of power management features, but it may be necessary to disable these features. Enabling power management on a NIC can cause connection issues, resulting in fatal errors within the software. More information is available in KB Article R10339, "Power Management Issues with Tabs3 and PracticeMaster Software Products."

Speed and Duplex Configurations  

Improper configuration of NIC link speeds and duplex settings can cause sluggish network performance, timeout errors and lost network connections, all of which can in turn lead to data corruption. It is important that each NIC, including those on the file server(s), are configured to match the speed and duplex settings used by the ports on the hubs or switches to which they are connected.

Many NICs, hubs and switches support auto-detection (also called auto-sensing and auto-negotiation), which automatically detects and matches the speed and duplex settings configured for the connected hub or switch port. However, auto-detection may not work correctly when connecting certain brands of NICs, hubs and switches to certain other brands. Therefore, it may be necessary to manually configure the NIC to match the exact speed and duplex settings used by the hub or switch port. The following article from Microsoft's Knowledge Base provide detailed information regarding speed and duplex settings:

• Microsoft Article 325487 - How to Troubleshoot Network Connectivity Problems

References  

• Microsoft Article 325487 - How to Troubleshoot Network Connectivity Problems
• KB Article R11262 - Statement on Novell NetWare Compatibility
• KB Article R11309 - Network Settings Technical Information
• KB Article R10011 - Troubleshooting Invalid Page Fault and Other Exception Errors

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