DB2 LUW: Intra-tablespace parallelism

Db2 V9.7 FP2: Intra-tablespace parallelism can reduce elapsed time for backups

Starting in Version 9.7 Fix Pack 2, intra-tablespace parallelism was introduced and can be used during backups other than delta and incremental backups. Intra-tablespace parallelism can reduce the time needed for a backup operation by allowing multiple threads to read the same table space in parallel during the whole backup operation.

When you use intra-tablespace parallelism, the table spaces are split into mutually exclusive page ranges. You enable and tune intra-tablespace parallelism using the Db2_ITP_LEVEL registry variable.

The environments that benefit the most from this enhancement are the ones in which the sizes of table spaces vary widely.

DB2_ITP_LEVEL

Operating system: All

Default: 0, Values: 0 - 64

This variable enables intra-tablespace parallelism, which provides additional parallel reading of data in a database-managed space (DMS) or automatic storage table space during backups other than incremental and delta backups. Intra-tablespace parallelism can reduce the time needed for online and offline backups. This variable is available in Version 9.7 Fix Pack 2 and later fix packs.

If you use the default setting (0), intra-tablespace parallelism is not enabled and each table space is assigned a single Db2 thread during backups. Use a setting of 0 to maintain the same behavior as in previous releases.

When intra-tablespace parallelism is enabled, the database manager splits the table spaces into ranges so that multiple Db2 threads can read concurrently each table space, as follows:

If you specify a value of 1, the database manager uses the table space information to determine the range size and the number of ranges to be read in parallel.

If you specify a value of 2 - 64, the database manager uses the table space information to determine a range size, but that size is divided by the value of the variable to determine the final range size.

This variable has no effect on SMS table spaces.