The Multi-Stream backup feature in PowerScale is an innovative feature that is unique to PowerScale. It is an order of magnitude improvement in backup throughput, management, and scalability. The feature automatically splits a backup dataset into multiple segments or streams. Each backup steam is sent simultaneously to its own tape media using parallel tree walks with integrated dynamic load balancing and fault tolerance between streams.
This feature eliminates the need to manually split a directory structure across multiple backup jobs, which is error-prone, time intensive, and difficult to evenly distribute due to varying directory sizes and file counts. Often, one or more backup jobs will be much larger than the others due to this uneven distribution leading to longer backup times. In comparison, streams within a Multi-Stream backup are not bound by directory borders, spits can even occur between files in the same directory.
As mentioned above, the Restartable feature is supported in conjunction with the Multi-Stream feature with Commvault 11 SP25+ and OneFS 184.108.40.206+.
Commvault has integrated with this feature. It is also enabled by default on NDMP backups of an PowerScale cluster when both the device streams value under the storage policy and the data readers value under the Subclient are greater than one.