New RMAN Compression Algorithm in 11g

We are already familiar with RMAN compression feature in 10g. As we all know, compression is CPU intensive activity. While backup is running, we can see high CPU utilization, sometimes reaching to 100%.

In 24x7 environments, we do not have special backup window. So we can see performance degradation, when compressed backups are running.

Oracle 11g addressed this problem, by introducing new ZLIB compression algorithm.

So based on our requirement, we can select an algorithm

1. ZLIB - for CPU efficiency (new)
2. BZIP2 - for maximum compression (default)

We can see the details of compression algorithm in V$RMAN_COMPRESSION_ALGORITHM view

SQL> SELECT ALGORITHM_NAME, IS_DEFAULT FROM V$RMAN_COMPRESSION_ALGORITHM
/

ALGORITHM_NAME IS_DEFAULT
--------------- ----------
ZLIB NO
BZIP2 YES

We can change the COMPRESSION ALGORITHM by using RMAN

RMAN> CONFIGURE COMPRESSION ALGORITHM 'ZLIB';

new RMAN configuration parameters:
CONFIGURE COMPRESSION ALGORITHM 'ZLIB';
new RMAN configuration parameters are successfully stored

We can validate the changed value by using

RMAN> show all;

To reset the value to default, we can use

RMAN> CONFIGURE COMPRESSION ALGORITHM CLEAR;

old RMAN configuration parameters:
CONFIGURE COMPRESSION ALGORITHM 'ZLIB';
RMAN configuration parameters are successfully reset to default value

NOTE: COMPATIBLE parameter must be set to 11.0.0 or higher for ZLIB compression