Veritas NetBackup™ Administrator's Guide, Volume II

Speed of the backup device

Backups that are sent to tapes with a transfer rate of 800 kilobytes per second are generally faster than tapes with a transfer rate of 400 kilobytes. (Assume that other factors allow for the faster transfer rate.)

Available network bandwidth

The available bandwidth is less than the theoretical network bandwidth and depends on how much other network traffic is present. For example, multiple backups occurring on the same network compete for bandwidth.

Speed with which the client can process the data

The speed varies with the hardware platform and depends on the other applications that run on the platform. File size is also an important factor. Clients can process larger files faster than smaller ones. A backup for 20 files, 1 megabyte each, is faster than a backup for 20,000 files that are 1 kilobyte each.

Speed with which the server can process the data

Like client speed, server speed also varies with the hardware platform and depends on the other applications that run on the platform. The number of concurrent backups being performed also affects server speed.

Network configuration can affect performance

For example, when some computers run full-duplex and some run half-duplex in an Ethernet environment, the throughput is significantly reduced.

Compression (on UNIX)

Software compression often multiplies the backup time by a factor of two or three for a given set of data.

Device delays

These delays can vary widely and depend on the devices and the computing environments.