The fileset zlibNX.rte contains an implementation of zlib with support for hardware compression through the NX (gzip) accelerator. The implementation is compatible with other implementations of zlib. This means

• • Files that were compressed with zlibNX can be decompressed with any other zlib implementation.
  • Files that were compressed with any other zlib implementation can be decompressed with zlibNX.

For AIX 7.2 TL4, the fileset zlibNX.rte can be found in the Expansion Pack for IBM AIX 7.2, which can be downloaded from the ESS website.

For AIX 7.2 TL5 or later, the fileset zlibNX.rte is part of the standard operating system and therefore no longer needs to be downloaded separately. In particular, zlibNX.rte is included in AIX 7.3.

The fileset can be installed with the “installp” command:

# installp -acd zlibNX.rte all
+-----------------------------------------------------------------------------+
                    Pre-installation Verification...
+-----------------------------------------------------------------------------+
Verifying selections...done
Verifying requisites...done
Results...
...
Installation Summary
--------------------
Name                        Level           Part        Event       Result
-------------------------------------------------------------------------------
zlibNX.rte                  7.2.4.10        USR         APPLY       SUCCESS   
zlibNX.rte                  7.2.4.10        ROOT        APPLY       SUCCESS   
# 

Attention: For the following versions of zlibNX.rte there is a problem that can lead to data loss:

• • zlibNX.rte:7.2.4.0-7.2.4.9
  • zlibNX.rte:7.3.0.0-7.3.0.3

Additional information and fixes for the issue are available at the following link: https://www.ibm.com/support/pages/node/7028659 (Potential undetected data loss by using zlibNX).

After installing the fileset, the availability of the NX (gzip) accelerator can be checked with the “nxstat” command:

$ nxstat -S
nx_accel_mask = 1

GZIP accelerator available
$

On an AIX system without NX Accelerator support (incorrect processor mode, old firmware, POWER8 or older), the output looks like this:

$ nxstat -S
nx_accel_mask = 0

** No accelerators available **
$

The libz library from zlibNX.rte, which supports hardware compression with NX (gzip) Accelerator, can be found in the following locations:

• • /usr/opt/zlibNX/lib/libz.a (dynamically linked version)
  • /usr/opt/zlibNX/static/lib/libz.a (statically linked version)