Cisco MDS-9124 Troubleshooting Guide - Page 34

Best Practices Chapter 1 Troubleshooting Overview Send documentation comments to [email protected] Best Practices Best practices are the recommended steps you should take to ensure the proper operation of your fabric. We recommend the following general best practices for most SAN fabrics: • Maintain a consistent Cisco SAN-OS release across all your Cisco MDS switches. • Refer to the release notes for your Cisco SAN-OS release for the latest features, limitations, and caveats. • Enable system message logging. See the "System Messages" section on page 1-10. • Troubleshoot any new configuration changes after implementing the change. • Use Fabric Manager and Device Manager to proactively manage your fabric and detect possible problems before they become critical. Troubleshooting Basics This section provides a series of questions that may be useful when troubleshooting a problem with a Cisco MDS 9000 Family switch or connected devices. Use the answers to these questions to plan a course of action and to determine the scope of the problem. For example, if a host can only access some, but not all, of the logical unit numbers (LUNs) on an existing subsystem, then fabric-specific issues (such as FSPF, ISLs, or FCNS) do not need to be investigated. The fabric components can therefore be eliminated from possible causes of the problem. This section contains the following topics: • General Steps, page 1-2 • Gathering Information Using Common Fabric Manager Tools and CLI Commands, page 1-3 • Verifying Basic Connectivity, page 1-4 • Verifying SAN Element Registration, page 1-5 • Fibre Channel End-to-End Connectivity, page 1-5 General Steps The two most common symptoms of problems in a storage network are: • A host cannot access its allocated storage • An application does not respond after attempting to access the allocated storage By answering the questions in the following subsections, you can determine the paths you need to follow and the components that you should investigate further. These questions are independent of host, switch, or subsystem vendor. Answer the following questions to determine the status of your installation: • Is this a newly installed system or an existing installation? (It could be a new SAN, host, or subsystem, or new LUNs exported to an existing host.) • Has the host ever been able to see its storage? • Does the host recognize any LUNs in the subsystem? • Are you trying to solve an existing application problem (too slow, too high latency, excessively long response time) or did the problem show up recently? Cisco MDS 9000 Family Troubleshooting Guide, Release 3.x 1-2 OL-9285-05