Oracle11新特性——备份恢复功能增强（二）

打算写一系列的文章介绍11g的新特性和变化。

Oracle11g在备份和恢复方面新增了很多的功能，无论是性能、功能性、安全性和可操作性方面都有了不同程度的提高。

这一篇介绍RMAN在备份级压缩方面的提高。

Oracle11新特性——备份恢复功能增强（一）：http://yangtingkun.itpub.net/post/468/412991

Oracle10g增加了对备份集压缩的功能，11g在这方面进行了增强，新增了另外一种压缩算法，这种新的压缩算法（ZLIB）提供更快的压缩效率，但是产生的压缩文件会比默认压缩算法（BZIP2）要大一些。

下面看一下两种压缩算法的对比：

$ rman target /

Recovery Manager: Release 11.1.0.6.0 - Production on Wed Nov 21 15:31:01 2007

connected to target database: TEST11G (DBID=790993044)

RMAN> report schema;

using target database control file instead of recovery catalog
Report of database schema for database with db_unique_name TEST11G

List of Permanent Datafiles
===========================
File Size(MB) Tablespace RB segs Datafile Name
---- -------- -------------------- ------- ------------------------
1 1024 SYSTEM *** /data/oracle/oradata/test11g/system01.dbf
2 1450 SYSAUX *** /data/oracle/oradata/test11g/sysaux01.dbf
3 2048 UNDOTBS1 *** /data/oracle/oradata/test11g/undotbs01.dbf
4 5 USERS *** /data/oracle/oradata/test11g/users01.dbf

List of Temporary Files
=======================
File Size(MB) Tablespace Maxsize(MB) Tempfile Name
---- -------- -------------------- ----------- --------------------
1 2048 TEMP 131071 /data/oracle/oradata/test11g/temp01.dbf

RMAN> backup tablespace system;

Starting backup at 21-NOV-07
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=56 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/data/oracle/oradata/test11g/system01.dbf
channel ORA_DISK_1: starting piece 1 at 21-NOV-07
channel ORA_DISK_1: finished piece 1 at 21-NOV-07
piece handle=/data/backup/0rj1k4qd_1_1 tag=TAG20071121T153124 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:36
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channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 21-NOV-07
channel ORA_DISK_1: finished piece 1 at 21-NOV-07
piece handle=/data/backup/0sj1k4s2_1_1 tag=TAG20071121T153124 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 21-NOV-07

RMAN> backup as compressed backupset tablespace system;

Starting backup at 21-NOV-07
using channel ORA_DISK_1
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/data/oracle/oradata/test11g/system01.dbf
channel ORA_DISK_1: starting piece 1 at 21-NOV-07
channel ORA_DISK_1: finished piece 1 at 21-NOV-07
piece handle=/data/backup/0tj1k4to_1_1 tag=TAG20071121T153312 comment=NONE