Configuring An Openstorage Storage Unit - Symantec NetBackup Manual

Property
Low water mark
Limit I/O streams
per volume

Configuring an OpenStorage storage unit

OpenStorage disk pool properties (continued)
Table 11-3
Description
The Low water mark is a threshold at which NetBackup stops image cleanup.
TheLow water mark setting cannot be greater than or equal to the High water mark
setting.
The default is 80%.
Select 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 for write operations,
if available. If not available, NetBackup queues jobs until a volume is available.
Too many streams may degrade performance because of disk thrashing. Disk thrashing
is excessive swapping of data between RAM and a hard disk drive. 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.
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 OpenStorage storage unit recommendations"
Configuring OpenStorage
Configuring an OpenStorage storage unit
on page 94.
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