NetServer Failures and Performance Problems Caused by PC or Network Problems

Resolving The Problem

This document includes suggestions to help NetServer users identify network problems that may cause NetServer failures. iSeries Software Support does not provide support for network problems. These include problems on the PC (for example, non-IBM software including Windows networking code, TCP stack, hardware, hardware drivers, and so on), hardware problems on the network (for example, networking cards, lines, switches, hubs, cables, and so on) and iSeries hardware problems. Network problems are outside the scope of iSeries Software Support. IBM Hardware support will assist with iSeries hardware problems.

Errors Caused by Network Problems

Network problems can cause NetServer performance problems and other failures, including connection problems, hangs, failure to respond, or errors received when trying to copy files to a NetServer drive. Error messages that may occur when trying to copy files to a NetServer network drive include the following:

o	Invalid MS DOS function
o	Network is busy
o	Cannot copy File
o	The path is too deep
o	Delayed write failed
o	Data has been lost

Failures may also be recorded in the Windows Event Log. The Windows XP Event Log may contain 'Event ID 50 with a source of MrxSMB'

Note: To access the Windows Event, log on Microsoft Windows 2000 or Windows XP, open Control Panel | Open Administrative Tools | Open Computer Management | Expand Event Viewer | Select System. Look at the columns labeled Source (for MrxSMB) and Event (for an ID of 50). On Windows 7, open Control Panel | Open Administrative Tools | Open Computer Management | Expand Event Viewer | Expand Windows Logs | Select System. For information on causes of these errors, refer to Microsoft document 321733 Delayed Write Failed Error Message When You Write a File to a Server and other Microsoft articles available on Microsoft's web site.

Network Incompatibility with iSeries Configuration

On IBM iSeries V5R2M0, line configuration settings for line speed (LINESPEED) and duplexing (DUPLEX) appear to be more sensitive than at previous releases. Performance and reliability can vary greatly depending on if these settings match the corresponding settings on the PC network (including settings on switches and routers). The iSeries line description LINESPEED or DUPLEX set to *AUTO does not work well if the router or switch is not set to *AUTO. On releases prior to V5R2M0, similar problems may be encountered but to a lesser extent.

For additional information, refer to IBM Technote N1016545 TCP/IP File Transfer is Slow - Linespeed, Duplex Problem.

Network Hardware Problems

Try swapping out hubs, switches, and so on.

Is the failing PC on the same LAN Segment as other working PCs? Try physically swapping them. Put the failing PC in the working location and vice versa.

PC and LAN Card Problems

Update to the latest Windows service pack for your Windows version.

Update to the latest version of driver for your Ethernet (LAN) card.

If the Ethernet card can be configured, try changing the link speed and duplex options.

Ensure the Windows TCP stack is current. Contact Microsoft for information on available TCP/IP stack fixes.

Useful Tools for Troubleshooting Network Problems:

The following tools can be used to troubleshoot network problems:

o	iSeries family server communications trace, LIC Trace, or TRCCNN. Any of these traces can help determine if the problem is within the iSeries family or on the network. Contact iSeries family Support Line for assistance in collecting any of these traces. Support can also run an analysis that will indicate if there are a lot of resends or missing or incomplete packets. Any of these are indications of network problems.
o	Network sniffer trace.
o	Microsoft's NETMON trace.

If you do not have a license to Microsoft NETMON or if you are using NetServer with the Linux Samba client, consider using Wireshark (formerly known as Ethereal). It is a free open source sniffer product. Refer to the following Web site for details: https://www.wireshark.org/ .