HP StorageWorks Enterprise Virtual Array Online Firmware Upgrade Best Practices (5697-6388, January 2007)

Storage sy stem u

tilization data analysis

When evaluatin

g the performance of the EVA, it is impor tant to distinguish between the two fundamental

types of I/O pat

terns: small block reads/writes and large block reads/writes.

If th e workload

is predominantly small block I/Os, it is important to examine I/Os per second (IOPS). If

theworkloadispredominantlylargeblockI/Os,itisimportanttoevaluatethethroughputinmegabytes

per second (MB/s).

A good technique for determining if the storage system is servicing predominantly large block versus

small block I/Os is to analyze the HP Command View EVAPerf output and divide the total MB/s by the

IOPS . This pr

ovides the average transfer size. When this result is less than 16 KB, the work load can

be considere

d predominately small block I/Os.

Small block transfers

In the situation where the workload is predominantly small block I/Os, the abilit y of the storage system

to ser vice workloads is primarily bounded by the number of I/Os processed in a given period of time,

which is typically measured in IOPS or I/Os per second.

The graph in Figure 7 shows a n example of an EVA8000 per forming an online controller ﬁrmware

upgrade with an OLTP work load, with an I/O size of 8 KB. In this example the total time that I/Os

are not being process is less than 30 seconds.

Figure 7 Small block transfer proﬁle

HP StorageWorks Enterprise Virtual Array online ﬁrmware upgrade best practices