VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Performance Monitoring and Tuning

Performance Guidelines

Chapter 12 387

The ﬁgure “Use of Striping for Optimal Data Access” shows an example

of a single volume (HotVol) that has been identiﬁed as a data-access

bottleneck. This volume is striped across four disks, leaving the

remaining space on these disks free for use by less-heavily used volumes.

Figure 12-1 Use of Striping for Optimal Data Access

Mirroring

NOTE You may need an additional license to use this feature.

Mirroring stores multiple copies of data on a system. When properly

applied, mirroring provides continuous availability of data and

protection against data loss due to physical media failure. Mirroring

improves the chance of data recovery in the event of a system crash or

the failure of a disk or other hardware.

In some cases, you can also use mirroring to improve I/O performance.

Unlike striping, the performance gain depends on the ratio of reads to

writes in the disk accesses. If the system workload is primarily

write-intensive (for example, greater than 30 percent writes), mirroring

can result in reduced performance.

Combining Mirroring and Striping

NOTE You may need an additional license to use this feature.

HotVol HotVol

PL1 SD3

Another

Disk 1 Disk 2 Disk 3 Disk 4

HotVol

PL1 SD4

Less

Important

Volume

HotVol

PL1 SD2

Lightly

Used

Volume

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