VERITAS Volume Manager 3.1 Administrator's Guide

Performance Monitoring
Performance Guidelines:
Chapter 9392
By striping this “high traffic” data across portions of multiple disks, you
can increase access bandwidth to this data.
Figure 9-1, Use of Striping for Optimal Data Access,, is an example of a
single volume (Hot Vol) that has been identified as being a data access
bottleneck. This volume is striped across four disks, leaving the
remainder of those four disks free for use by less-heavily used volumes.
Figure 9-1 Use of Striping for Optimal Data Access
Mirroring
NOTE You may need an additional license to use this feature.
Mirroring is a technique for storing multiple copies of data on a system.
When properly applied, mirroring canbe used to provide continuous data
availability by protecting against data loss due to physical media failure.
The use of mirroring improves the chance of data recovery in the event of
a system crash or disk failure.
In some cases, mirroring can also be used to improve system
performance. Mirroring heavily-accessed data not only protects the data
from loss due to disk failure, but can also improve I/O performance.
Unlike striping however, performance gained through the use of
mirroring depends on the read/write ratio of the disk accesses. If the
system workload is primarily write-intensive (for example, greater than
Hot Vol Hot Vol
PL1 SD3
Another Volume
Disk 1 Disk 2 Disk 3 Disk 4
Hot Vol
PL1 SD4
Less
Important
Volume
Hot Vol
PL1 SD2
Lightly
Used
Volume
Home
Directory
Volume
Cool Volume
PL1 SD1