Maximizing Performance of IBM DB2 Backups  ® This IBM ®  Redbooks ®  Analytics Support Web Doc describes how to maximize the performance of IBM  DB2®  backups. Backing up a database is a critical part of any disaster recovery plan. Making sure that the backup  completes in a reasonable time frame means that there is always a valid backup available in case of  emergency. This document describes the following elements that are critical to good backup  performance: The backup process model  z Basic backup performance concepts z Backup performance considerations z Monitoring backup performance with the  DB2_BAR_STATS  registry variable z This document applies to all versions of DB2 for Linux, UNIX, and Windows.  The backup process model consists of the engine dispatchable units (EDUs)  db2agent ,  db2bm , and  db2med . If the backup uses a storage manager, an additional  db2vend  process is created. The  db2agent  EDU does most of its work during the start of the backup, and then waits for the backup to  complete. The tasks that it performs include the following actions: The backup process model The  db2bm  EDU acquires a backup buffer from the empty queue, and then fills the buffer by reading data  from its assigned table space. The  db2bm  then places the backup buffer on the full queue to be written to  the backup device by the  db2med  EDU.  The  db2med  EDU is responsible for acquiring a backup buffer from the full queue and writing it to the  backup device. If the backup is being written to disk, it handles the input/output (I/O) directly. If the backup  is being written to a storage manager, it transfers the full buffer to the  db2vend  process. After  confirmation that the  db2vend  process successfully saved the contents of the buffer, the  db2med  EDU  returns the backup buffer to an empty queue for reuse by the next  db2bm  EDU. The  db2vend  process is created by the  db2med  EDU if a storage manager is being used. The  db2vend process receives a full buffer from the  db2med , and calls the appropriate vendor application programming  interface (API) for sending the data to the storage manager. A separate process is used so that any crash  or abnormal failure during interaction with the storage manager terminates only the  db2vend  process,  and does not negatively affect the stability of the DB2 instance. Maximizing Performance of IBM DB2 Backups Calculate and create an optimal number of  db2bm  and  db2med  EDUs z Allocate an optimal number of optimally sized backup buffers z Display the selected tunable values to the  db2diag.log z Allocate message queues for inter-EDU communication z Create a list of table spaces that are sorted by decreasing size z Coordinate the backup process by sending control messages to the  db2bm  and  db2med  EDUs z 1