Log sequence numbers in DB2 pureScale® environments

DB2® databases use the log sequence number (LSN), a 64-bit identifier, to determine the order of the operations that generated the log records.

The LSN is an ever-increasing value. Each member writes to its own set of log files (a log stream), and the LSN within a single log stream is a unique number.

Because LSNs are generated independently on each member and there are multiple log streams, it is possible to have duplicate LSN values across different log streams. A log record identifier (LRI) is used to identify log records across log streams; each log record in any log stream in the database is assigned a unique LRI. Use the db2pd command to determine which LRI is being processed by a recovery operation.