RMAN中MAXSETSIZE和MAXPIECESIZE的用法，
MAXSETSIZE跟MAXPIECESIZE用法
区别：maxpiecesize设置的是备份完成后的备份片大小，对备份整体的大小没有影响，比如一个G的备份完成文件，maxpiecesize设置为100M，最后就会变成10个100M的备份文件。Maxsetsize设置限定的是整体大小，个人认为这个功能比较鸡肋，一般只要没人动，就用不到的。
Maxsetsize的写法：
1.
RMAN> configure maxsetsize to 2G;
RMAN> run{
2> allocate channel c1 device type disk;
3> backup database format='/u01/app/oracle/oradata/Backup/oradb_%d_%s.bak';
4> release channel c1;
5> }
2.
run{
allocate channel c1 device type disk ;
backup database maxsetsize 1000M format='/u01/app/oracle/oradata/Backup/oradb_%d_%s_%p.bak';
release channel c1;
}
清除maxsetsize的语句：RMAN> CONFIGURE MAXSETSIZE clear;
Maxpiecesize的写法：
run{
allocate channel c1 device type disk MAXPIECESIZE 100M;
backup database format='/u01/app/oracle/oradata/Backup/oradb_%d_%s_%p.bak';
release channel c1;
}
然后每个文件都是100M
[oracle@orcl Backup]$ ls -lh
total 1.2G
-rw-r----- 1 oracle oinstall 100M Dec 24 03:01 oradb_ORCL_117_10.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:01 oradb_ORCL_117_11.bak
-rw-r----- 1 oracle oinstall 71M Dec 24 03:01 oradb_ORCL_117_12.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 02:59 oradb_ORCL_117_1.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 02:59 oradb_ORCL_117_2.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 02:59 oradb_ORCL_117_3.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_4.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_5.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_6.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_7.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_8.bak
-rw-r----- 1 oracle oinstall 100M Dec 24 03:00 oradb_ORCL_117_9.bak
-rw-r----- 1 oracle oinstall 9.7M Dec 24 03:01 oradb_ORCL_118_1.bak