Data Streams are used to move data from source to destination. The source can be production data or Commvault protected data. A destination stream will always move to Commvault protected storage. Understanding the data stream concept will allow a CommCell® environment to be optimally configured to meet protection and recovery windows.
Stream settings are configured in various places within the CommCell® console including the storage policy, MediaAgent, subclient, and library. The system always uses the lowest setting. If a MediaAgent is configured to receive as many as 100 streams and one storage policy is writing through the MediaAgent and is configured to use 0five streams, then only 50 streams will be sent through the MediaAgent.
During a data protection job, streams originate at the source file or application that is being protected. One or more read operations are used to read the source data. The number of read operations is determined by the number of subclients and within each subclient, the number of data readers or data streams, depending on which agent is managing the data. Once the data is read from the source it is processed by the agent and then sent to the MediaAgent as job streams. The MediaAgent then processes the data, arranges the data into chunks and writes the data to storage as device streams. The data is written to storage based on the number of writers, for a disk library, or devices (tape drives) for a tape library.
Stream management high level overview