RMAN：
使用ramn进行备份和恢复，rman不依赖系统操作命令，在数据块级别做备份。块级别备份，能只备份变化后的块，实现增量备份。而且不会备份空的块。
好处:
1、能实现增量备份
2、只备份有数据的块，不备份空块和未使用的块
3、支持压缩算法，进一步压缩数据
4、帮我们管理备份的元数据
SQL> create tablespace test datafile '/data/oracle/oradata/orcl/test01.dbf' size 100M; #创建表空间，具体目录，可通过之前查找确定
Tablespace created.
SQL>
SQL> create table test tablespace test as select * from scott.emp; # 创建表 table
Table created.
SQL>
SQL> select table_name from dba_tables
SQL> analyze table test compute statistics;
where tablespace_name='TEST'
SQL> desc dba_tables; # 分析完表后，就能看到有 AVG_ROW_LEN参数，平均行长，就是一行占多少字节；
SQL> select AVG_ROW_LEN*NUM_ROWs from dba_tables
where table_name='TEST'; # 用平均行长*总共多少行，来计算table的大小，单位字节。
SQL> select * from dba_data_files; 能看到表所属数据文件的的文件号
FILE_NAME FILE_ID TABLESPACE_NAME BYTES BLOCKS
-------------------------------------------------- ---------- ------------------------------------------------------------ ---------- ----------
STATUS RELATIVE_FNO AUTOEX MAXBYTES MAXBLOCKS INCREMENT_BY USER_BYTES USER_BLOCKS ONLINE_STATUS
------------------ ------------ ------ ---------- ---------- ------------ ---------- ----------- --------------
/data/oracle/oradata/orcl/test01.dbf 6 TEST 104857600 12800
AVAILABLE 6 NO 0 0 0 103809024 12672 ONLINE
显示TEST的数据文件，文件为6；
在RMAN下：
[oracle@localhost ~]$ rman target /
RMAN> backup datafile 6; #用rman来备份文件号为6，就是TEST。
Starting backup at 15-NOV-17
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=50 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=00006 name=/data/oracle/oradata/orcl/test01.dbf
channel ORA_DISK_1: starting piece 1 at 15-NOV-17
channel ORA_DISK_1: finished piece 1 at 15-NOV-17
piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp tag=TAG20171115T222358 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 15-NOV-17
RMAN>
[oracle@localhost orcl]$ ls -lh |grep test
-rw-r-----. 1 oracle dba 101M Nov 15 22:23 test01.dbf
[oracle@localhost orcl]$ cd /data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/ # rman备份文件目录，备份时会显示
[oracle@localhost 2017_11_15]$ ls -lh |grep o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp
-rw-r-----. 1 oracle dba 1.1M Nov 15 22:23 o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp
[oracle@localhost 2017_11_15]$
会发现test01.dbf有101M，而rman备份的文件只有1.1M.
RMAN> backup as compressed backupset datafile 6; # rman压缩备份，元数据压缩不了，主要是压缩数据。 因此rman除了自动过滤不备份空快外，还支持压缩算法，进一步节省空间。
Starting backup at 15-NOV-17
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=49 device type=DISK
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00006 name=/data/oracle/oradata/orcl/test01.dbf
channel ORA_DISK_1: starting piece 1 at 15-NOV-17
channel ORA_DISK_1: finished piece 1 at 15-NOV-17
piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222847_f0rmrzqv_.bkp tag=TAG20171115T222847 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 15-NOV-17
RMAN>
RMAN> list backup; # 列出做过哪些备份，备份类型，备份大小，备份到哪里，备份是SCN
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1 Full 1.07M DISK 00:00:00 15-NOV-17
BP Key: 1 Status: AVAILABLE Compressed: NO Tag: TAG20171115T222358
Piece Name: /data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp
List of Datafiles in backup set 1
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
6 Full 1048680 15-NOV-17 /data/oracle/oradata/orcl/test01.dbf
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
2 Full 1.02M DISK 00:00:00 15-NOV-17
BP Key: 2 Status: AVAILABLE Compressed: YES Tag: TAG20171115T222847
Piece Name: /data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222847_f0rmrzqv_.bkp
List of Datafiles in backup set 2
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
6 Full 1048852 15-NOV-17 /data/oracle/oradata/orcl/test01.dbf
RMAN>
RMAN> delete backup; # 删除数据
using channel ORA_DISK_1
List of Backup Pieces
BP Key BS Key Pc# Cp# Status Device Type Piece Name
------- ------- --- --- ----------- ----------- ----------
1 1 1 1 AVAILABLE DISK /data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp
2 2 1 1 AVAILABLE DISK /data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222847_f0rmrzqv_.bkp
Do you really want to delete the above objects (enter YES or NO)? yes
deleted backup piece
backup piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222358_f0rmhz7o_.bkp RECID=1 STAMP=960157439
deleted backup piece
backup piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T222847_f0rmrzqv_.bkp RECID=2 STAMP=960157727
Deleted 2 objects
RMAN>
RMAN> backup database; # 普通全备，它会自己找控制文件，数据文件，备份时显示路径信息，
Starting backup at 15-NOV-17
using channel ORA_DISK_1
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/orcl/system01.dbf
input datafile file number=00002 name=/data/oracle/oradata/orcl/sysaux01.dbf
input datafile file number=00005 name=/data/oracle/oradata/orcl/example01.dbf
input datafile file number=00006 name=/data/oracle/oradata/orcl/test01.dbf
input datafile file number=00003 name=/data/oracle/oradata/orcl/undotbs01.dbf
input datafile file number=00004 name=/data/oracle/oradata/orcl/users01.dbf
channel ORA_DISK_1: starting piece 1 at 15-NOV-17
channel ORA_DISK_1: finished piece 1 at 15-NOV-17
piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_nnndf_TAG20171115T223737_f0rn9kr1_.bkp tag=TAG20171115T223737 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:05
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 15-NOV-17
channel ORA_DISK_1: finished piece 1 at 15-NOV-17
piece handle=/data/oracle/flash_recovery_area/ORCL/backupset/2017_11_15/o1_mf_ncsnf_TAG20171115T223737_f0rncn59_.bkp tag=TAG20171115T223737 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 15-NOV-17
RMAN>
RMAN> backup as compressed backupset database; #压缩全备