HP Data Protector Software Performance White Paper

Figure 45 shows that asynchronous reading resulted in a disk queue length between 18 and 50.

Figure 45. Smart array configuration of backup server – one RAID 1+0 logical drive with 4 SAS disks

Device and media options

You can set advanced options for devices and media when configuring a new device, or when

changing device properties. The availability of these options depends on the device type.

You can also set some of these options when configuring a backup, for example, the

concurrency. Device options set in a backup specification override options set for the device in

general.

The most relevant options for performance are:

• Concurrency

• CRC check

• Block size

• Segment size

• Disk Agent buffers

• Hardware compression

Concurrency

The number of Disk Agents started for each Media Agent is called Disk Agent (backup)

concurrency and can be modified using the advanced options for the device or when configuring

a backup. The concurrency set in the backup specification takes precedence over the

concurrency set in the device definition.

Data Protector provides a default number of Disk Agents that are sufficient for most cases. The

fast HP StorageWorks Ultrium 960 drive is configured with a default of four.

For example, if you have a

library with two Ultrium 960 drives, each controlled by a Media

Agent, and each Media Agent receives data from four Disk Agents concurrently, data from eight

disks is backed up simultaneously.