In the SAN environment , the Logical Disk Performance objects counters monitor the logical partitions.

 I use the Logical Disk Read Bytes/sec  as a starting point when I troubleshoot Disk IO issues. If I can isolate the activity , this gives me a good guideline as to Read rates from the SAN as viewed from the OS.

 The Logical Disk Read Bytes/sec  and the Logical Disk Writes Bytes/sec  display rates of transfer for read\write .

Check SQL Server – Backup to NUL trick - read throughput as an example of how to use the counter to troubleshoot disk IO .

Use Perfmon to initiate a monitor. Isolating the activity onto one disk and stopping all other activity is a good starting point to define the rates.

See Also

Window Perfmon scripting, SQL Server perfmon and how to perfmon

IO_completion on disk solved with Wait Stats and Perfmon

Author: Jack Vamvas (http://www.sqlserver-dba.com)