Notes on Limit Jobs Per Policy

The number of concurrent backup jobs that NetBackup can perform depends on:

• Number of storage devices available and multiplexing limits. To process more than one backup job at a time, your configuration must include more than one storage unit, or a storage unit with enough drives to perform more than one backup at a time, or storage units configured to multiplex. With removable media devices such as tape drives, this depends on the total number of drives in the storage units. With magnetic disk, the storage device is defined as a file path and the available disk space determines how many paths are possible.
• Server speed. Too many concurrent backups interfere with the performance of the server. The best number depends on the hardware, operating system, and applications that are running.
• Network loading. The available bandwidth of the network determines how many backups can occur concurrently. If you encounter loading problems, consider backing up over multiple networks or using compression.

A special case exists when backing up a client that is on the same machine as the server. Here, network loading is not a factor because you do not use the network. Client and server loading, however, is still a factor.

• Multiplexing. If you use multiplexing, set Limit Jobs Per Policy high enough to support the specified level of multiplexing.

Lower values can limit multiplexing within a policy if there are jobs from different schedules within that policy. For example, if Limit Jobs Per Policy is at 2 and an incremental backup schedule is due to run for four clients, only two are backed up at a time, regardless of multiplexing settings.

• Limit Jobs Per Policy does not prevent concurrent jobs if the jobs are from different policies.

For example, if there are three policies and each has its Limit Jobs Per Policy at 2, NetBackup can start two jobs from each policy and have a total of six running at one time.