Thursday 2 March 2017

RMAN Compression Algorithms in 11gR2

·   BASIC – default compression algorithm
·   HIGH – Best suited for backups over slower networks where the limiting factor is network speed
·   MEDIUM -Recommended for most environments. Good combination of compression ratios and speed
·   LOW – Least impact on backup throughput and suited for environments where CPU resources are the limiting factor.

SQL> select * from V$RMAN_COMPRESSION_ALGORITHM;

ALGORITHM_ID ALGORITHM_NA INITIAL_RELEASE    TERMINAL_RELEASE   ALGORITHM_DESCRIPTION                                        ALGORITHM_COMPATIB IS_ REQ IS_DEFAULT
------------ ------------ ------------------ ------------------ ------------------------------------------------------------ ------------------ --- --- --------------------
           0 BZIP2        10.0.0.0.0         11.2.0.0.0         good compression ratio                                       9.2.0.0.0          YES NO  NO
           1 BASIC        10.0.0.0.0                            good compression ratio                                       9.2.0.0.0          YES NO  YES
           2 LOW          11.2.0.0.0                            maximum possible compression speed                           11.2.0.0.0         YES YES NO
           3 ZLIB         11.0.0.0.0         11.2.0.0.0         balance between speed and compression ratio                  11.0.0.0.0         YES YES NO
           4 MEDIUM       11.2.0.0.0                            balance between speed and compression ratio                  11.0.0.0.0         YES YES NO
           5 HIGH         11.2.0.0.0                            maximum possible compression ratio                           11.2.0.0.0         YES YES NO
6 rows selected.
  
Set RMAN configuraton for compresion algorithim type:
RMAN> CONFIGURE COMPRESSION ALGORITHM ‘ZLIB’;
new RMAN configuration parameters:
CONFIGURE COMPRESSION ALGORITHM ‘ZLIB’;
new RMAN configuration parameters are successfully stored
(or)
RMAN> CONFIGURE COMPRESSION ALGORITHM ‘HIGH’;
(or)
RMAN> CONFIGURE COMPRESSION ALGORITHM 'MEDIUM';
(or)
RMAN> CONFIGURE COMPRESSION ALGORITHM ‘LOW’;
(or)
RMAN> CONFIGURE COMPRESSION ALGORITHM ‘BASIC’;


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

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

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