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 24×7 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

Addition for Oracle 11gR2
=========================

In Oracle 11gR2, new set of compression algorithms are introduced

column algorithm_name format a15
column algorithm_description format a50

SQL> select algorithm_name, algorithm_description from v$rman_compression_algorithm
/

algorithm_name algorithm_description
————— ————————————————–
BASIC good compression ratio
LOW maximum possible compression speed
MEDIUM balance between speed and compression ratio
HIGH maximum possible compression ratio

NOTE: “IS_DEFAULT” column is removed from v$rman_compression_algorithm view. BASIC is the default algorithm used for compression.

Advertisements
This entry was posted in Oracle Database Backup, Oracle Recovery Manager and tagged . Bookmark the permalink.

One Response to New RMAN Compression Algorithm in 11g

  1. pbsl says:

    you have a nice site. thanks for sharing this site. you can download lots of ebook from here

    http://feboook.blogspot.com

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s