Configuring An Advanceddisk Storage Unit - Symantec NetBackup Manual

32 Configuring AdvancedDisk

Configuring an AdvancedDisk storage unit

Configuring an AdvancedDisk storage unit
AdvancedDisk disk pool properties (continued)
Table 4-4
Property
Limit I/O streams
per volume
Create one or more storage units that reference the disk pool.
The Disk Pool Configuration Wizard lets you create a storage unit; therefore,
you may have created a storage unit when you created a disk pool. To determine
if storage units exist for the disk pool, see the NetBackup Management > Storage
> Storage Units window of the NetBackup Administration Console.
See About AdvancedDisk storage unit recommendations"
More information about storage units is available.
See the NetBackup Administrator's Guide for Windows, Volume I.
See the NetBackup Administrator's Guide for UNIX and Linux, Volume I.
Description
Select this option to limit the number of read and write streams
(that is, jobs) for each volume in the disk pool. A job may read
backup images or write backup images. By default, there is no
limit.
When the limit is reached, NetBackup chooses another volume,
if available. If not available, NetBackup queues jobs until a volume
is available.
Too many jobs that read and write data may degrade disk
performance because of disk thrashing. (Disk thrashing is when
the read and write heads move between the cylinders excessively
as they seek the data for competing jobs.)
Fewer streams can improve throughput, which may increase the
number of jobs that complete in a specific time period.
Select or enter the number of read and write streams to allow per
volume.
Many factors affect the optimal number of streams. Factors include
but are not limited to disk speed, CPU speed, and the amount of
memory.
on page 35.