HP Data Protector Software Performance White Paper

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the backup session. If you selected the load balancing option in the Create New Backup dialog
(the default), it cannot be deselected.
Figure 33 illustrates a backup configuration with the default load balancing switched ON.
Figure 33. Backup configuration – load balancing
If load balancing was not selected (OFF) in the Create New Backup dialog, you can choose
single devices to be used for each object in a backup specification. This could be very beneficial
for bundling objects (such as file systems) based on their speed rather than their size. Data
Protector does not track the backup speed of each object and so cannot automatically balance
based on that. But the manual load balancing option provides an alternative solution for fine
tuning the distribution of backup objects to devices.
Software compression
This option enables compression of the data that is read by the Disk Agent. It is based on the
Lempel-Ziv compression algorithm, which is compatible with the standard UNIX compress utility.
Software compression could be an advantage in network environments with small bandwidths
when the network is the bottleneck. The Disk Agent compresses the data and subsequently
sends it across the network to the remote Media Agent. Sometimes this procedure improves the
backup performance. The default compression value is OFF.
Note: Most modern backup devices provide built-in hardware compression that you can
configure when adding the device to a client. If this is the case, do not use the software
compression option, since double compression only decreases performance without giving
better compression results.