rman 恢复数据错误案例--ORA-19573 错误

系统环境：

操作系统： AIX 5300-08
Oracle：  Oracle 10.2.0.1.0

错误现象：

RMAN> restore datafile 4;

Starting restore at 20-MAY-14

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=139 devtype=DISK

channel ORA_DISK_1: starting datafile backupset restore

channel ORA_DISK_1: specifying datafile(s) to restore from backup set

restoring datafile 00004 to /u01/app/oracle/oradata/prod/users01.dbf

channel ORA_DISK_1: reading from backup piece /backup/inc0_PROD_2qp8omr6_1_1

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of restore command at 05/20/2014 12:19:41

ORA-19870: error reading backup piece /backup/inc0_PROD_2qp8omr6_1_1

ORA-19573: cannot obtain exclusive enqueue for datafile 4

一直以为是备份有问题，没有找到备份的数据文件！

原来是DataBase 在open下，忘了将datafile offline，造成此低级错误；将数据文件offline 后，问题解决！