New undocumented parameter Savegroup Parallelism
With NetWorker 6.1 a new parameter was introduced for the savegroup resource. Savegroup Parallelism. This parameter for a NetWorker savegroup defines the maximum number of active backup processes (number of save streams) that can be activated by this specific savegroup at the same time. Figure 1 shows the entry for the Windows administrator GUI.
This value has been implemented for load balancing reasons. In the past there was the possibility that one savegroup or very few groups could claim all streams for itself (themselves). As a consequence, it was not possible to run multiple groups in parallel and effectively.
If the value is not zero, then it overrides any other parallelism considerations that savegroup may use to avoid over utilising the system's resources. Modifying the value has no effect on currently running savegroups. The value must be between 0 and 1000.
How does parallelism work?
In general, NetWorker save streams will be managed by the FIFO (first-in-first-out) principle which means that they will be served in the sequence they will be opened. As a consequence, if multiple groups are started at the same time, it is most obvious that these save streams will be unequally distributed among the groups. It can even be possible that one group takes all possible save streams for itself which will lead to the scenario, that the other groups are active but actually do nothing.
To ensure that only a certain maximum number of save streams will be opened by this group, you may not set the Savegroup Parallelism to a certain value.
- The default value is 0, which means that the old principle (no limitation) is active,
- Savegroup Parallelism has been introduced in NetWorker 6.1 but it has not yet been mentioned in any documentation.