Rman backup: compression

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Introduction

There are 4 levels of compression for rman: BASIC, LOW, MEDIUM and HIGH. BASIC is free and the others require the "Advanced Compression" license.

How to configure backup compression

You can find out the current setting with the statement below:

RMAN> show compression algorithm;

using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name PRDDB are:
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default

You can change this configuration as follows:

RMAN> CONFIGURE COMPRESSION ALGORITHM 'LOW';

old RMAN configuration parameters:

CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE;

new RMAN configuration parameters:

CONFIGURE COMPRESSION ALGORITHM 'LOW' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE;

new RMAN configuration parameters are successfully stored

How to perform a compressed backup

You use the same statement for any of the 4 backup settings. The statement simply applies the type of compression that is configured:

RMAN> backup as compressed backupset database plus archivelogs delete input;

Backup figures

The backup sizing and performance depends per system. So you will have to do some reseach yourself. But see below some info I got from another website. It turns out that the BASIC compression is not too bad,

Compression level	Backup Size	Backup Duration
=======================================================
NORMAL     		4 GB		279 sec
BASIC			636 MB		419 sec
LOW			797 MB		189 sec
MEDIUM			674 MB		238 sec
HIGH			485 MB		3129 sec