Accelerated SAN Essentials
© 2010 Hewlett-Packard Development Company, L.P.
Complicating the task of delivering good performance is the lack of meaningful
performance measurement standards. Although vendors and analysts often cite
benchmarks such as high rates of I/O and cache hits or low seek times on disk
drives as examples of good performance, these statistics offer little insight to SAN
A number of factors contribute to the difficulties an administrator has in gathering
and interpreting accurate performance data. The biggest issue is the collection of
performance statistics. This data may be spread across every component in the SAN
— the database, the operating system, the host bus adapter (HBA), the switch, and
the storage array. SAN administrators need to verify that they have gathered all of
the data required before beginning analysis.
It is imperative to make sure the clocks of the components being measured are all
synchronized. A few minutes difference, or even a few seconds, on any of the
internal time clocks in the components could distort the interpretation of the results.
There are many tools available on the market that measure performance in a SAN.
However, performance-tuning software can create a new set of performance
problems by slowing down the SAN.