User Manual

Fabric OS 5.0.0 procedures user guide 181
13 Troubleshooting
This chapter contains the following sections:
• Most common problem areas, page 182
• Gathering information for technical support, page 182
• Analyzing connection problems, page 184
• Restoring a segmented fabric, page 186
• Correcting zoning setup issues, page 187
• Recognizing MQ-WRITE errors, page 189
• Correcting I2C bus errors, page 190
• Correcting device login issues, page 191
• Identifying media-related issues, page 194
• Correcting link failures, page 196
• Correcting marginal links, page 198
• Inaccurate information in the system message log, page 200
• Recognizing the port initialization and FCP auto discovery process, page 200
Troubleshooting should begin at the center of the SAN — the fabric. Because switches are located
between the hosts and storage devices, and have visibility into both sides of the storage network, starting
with them can help narrow the search path. After eliminating the possibility of a fault within the fabric,
see if the problem is on the storage side or the host side, and continue a more detailed diagnosis from
there. Using this approach can quickly pinpoint and isolate problems.
For example, if a host cannot see a storage device, run a switch command to see if the storage device is
logically connected to the switch. If not, focus first on the storage side. Use storage diagnostic tools to
better understand why it is not visible to the switch. When the storage can be seen from the switch, if the
host still cannot see the storage device, then there is still a problem between the host and switch.
This chapter provides information on troubleshooting and the most common procedures used to diagnose
and repair issues. It also includes specific troubleshooting scenarios as examples.