Cisco MDS-9124 Troubleshooting Guide - Page 545

Appendix B Troubleshooting Tools and Methodology Using Host Diagnostic Tools Send documentation comments to [email protected] Alternatively, you can use Iometer, an I/O subsystem measurement and characterization tool, to generate a simulated load and measure performance. Iometer is a public domain software utility for Windows, originally written by Intel, that provides correlation functionality to assist with performance analysis. Iometer measures the end-to-end performance of a SAN without cache hits. This can be an important measurement because if write or read requests go to the cache on the controller (a cache hit) rather than to the disk subsystems, performance metrics will be artificially high. You can obtain Iometer from SourceForge.net at the following URL: http://sourceforge.net/projects/iometer/ Iometer is not the only I/O generator you can use to simulate traffic through the SAN fabric. Other popular I/O generators and benchmark tools used for SAN testing include Iozone and Postmark. Iozone is a file system benchmark tool that generates and measures a variety of file operations. It has been ported to many systems and is useful for performing a broad range of file system tests and analysis. Postmark was designed to create a large pool of continually changing files, which simulates the transaction rates of a large Internet mail server. PostMark generates an initial pool of random text files in a configurable range of sizes. Creation of the pool produces statistics on continuous small file creation performance. Once the pool is created, PostMark generates a specified number of transactions, each of which consists of a pair of smaller transactions: • Create file or Delete file • Read file or Append file Benchmarking tools offer a variety of capabilities and you should select the one that provides the best I/O characteristics of your application environment. Utilities provided by the Sun Solaris operating system let you determine if the remote storage has been recognized and exported to you in form of a raw device or mounted file system, and to issue some basic queries and tests to the storage. You can measure performance and generate loads using the iostat utility, the perfmeter GUI utility, the dd utility, or a third-party utility like Extreme SCSI. Every UNIX version provides similar utilities, but this guide only provides examples for Solaris. Refer to the documentation for your specific operating system for details. OL-9285-05 Cisco MDS 9000 Family Troubleshooting Guide, Release 3.x B-29