Maximum number of streams per volume: The value determines the number of backup streams that are deployed for backing up each volume. For example, If a policy contains 10 volumes and the value of this parameter is set to 4, then you see group of 4 backup streams for each volume, thereby total of 40 child backup streams and 10 parent backup streams as part of backup execution of the policy.

Maximum number of files in a batch: The value determines the maximum number of files that processed in a single burst by any stream. The files in a batch are processed sequentially within the stream. For example, Value of 300 for this parameter means that every stream is assigned maximum of 300 files in a single batch. So if a volume has one million files to be backed up and 4 streams assigned, then every stream is assigned 300 files each to begin with and then subsequently the streams are fed with 300 more files as and when they are ready for more backup processing.