Hardware accelerated backup and log file compression

By using the nest accelerator NX842 of POWER 7+ and POWER 8 processors, you can achieve hardware compression for backup images and log archive files on AIX® .


  • This solution is only supported on AIX. Minimum AIX levels are AIX V7 TL3 SP3 and AIX V6 TL9 SP3.
  • Active Memory Expansion (AME) has to be licensed but must not be enabled. This is a temporary restriction and not a technical limitation. In addition, Active Memory Sharing (AMS) has to be deactivated on the logical partition (LPAR).
  • The CPU has to be a POWER 7+ or later.
  • The following minimum firmware levels are recommended for POWER 8: FW820.50, FW830.30 or FW840.40.
    Remember: Provided that the kernel requirements are met, it is possible to recover using the backup images and log files that were compressed with NX842 on previous POWER® versions.

Advantages of using this solution

  • A very fast compression can be achieved through the special hardware compression unit NX842 on POWER CPUs. The general CPU resources are not used for this compression.
  • The NX842 compression units are typically not used for AME on database servers since deep row compression, adaptive compression and index compression can make memory compression inefficient.
  • The compression algorithm in hardware provides faster compression than the common Db2® compression.

How to use this as backup

To start a backup using the hardware compression, it is necessary to specify the library: backup database databasename compress comprlib libdb2nx842.a

The backups can be compressed by default with NX842. To achieve this the registry variable DB2_BCKP_COMPRESSION has to be set to NX842. Afterwards, issue the command: backup database databasename compress. The image will then be compressed using the NX842 hardware compression.

Using the solution for log archive compression

The NX842 hardware compression can also be used for log archive compression. To activate this, change the database configuration parameter LOGARCHCOMPR1 or LOGARCHCOMPR2 to NX842 using this command: update database configuration for databasename using LOGARCHCOMPR1 NX842
Note: These two parameters can still take different values. For example, the common Db2 compression can be used for LOGARCHCOMPR1 and NX842 compression for LOGARCHCOMPR2:
update database configuration for databasename using LOGARCHCOMPR1 ON
update database configuration for databasename using LOGARCHCOMPR2 NX842
For more information on NX842 compression, refer to POWER NX842 Compression for Db2.