3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

InForm OS Version 2.2.4 3PAR InForm OS Concepts Guide

20.1

System Tuner

The 3PAR System Tuner is an optional InForm OS feature that allows you to identify over-

utilized physical disks as candidates for load balancing and to then perform load balancing on

those disks. 3PAR System Tuner requires the use of the InForm CLI and also requires a 3PAR

System Tuner license.

As discussed in Chapter 2, Overview, virtual volumes are made up of multiple logical disks,

where each logical disk contains several chunklets. Chunklets are striped across multiple

physical disks. Generally, a system contains several virtual volumes. The I/O to each volume is

striped across several physical disks, thereby increasing the throughput of the volume. If the

performance of one or more disks degrades, the throughput of the logical disks, virtual

volumes, and ultimately the system, may also degrade.

There are two general reasons why physical disks have degraded performance:

■ The physical disk is a bad disk. A bad disk typically has unusually high maximum service

times compared to other good disks.

■ The physical disk has reached it maximum throughput due to unbalanced load. A disk in

this state typically has unusually high average service times as compared to good disks.

For instructions on how to identify over-utilized physical disks as candidates for load balancing

and demonstrations on how to perform load balancing on those disks see the InForm OS CLI

Administrator’s Manual.