RMAN删除失效的备份时报错故障处理

背景：

• 客户的数据库，之前一直是通过商用备份软件，备份到外置的磁带库内的，因为一些原因，磁带设备要淘汰，然后干脆利落地把磁带库下电搬走；

• 在此之前有一台备份服务器专门备份此数据库服务器，数据备份到磁带库设备里，后来，在数据库端没有做任何动作的情况下，备份服务器被拆除，在数据库服务器上的备份客户端也被卸载；

• 因此，RMAN无法再联系到sbt通道，也意味着list backup里的所有信息均无效；

• 现在想把list backup的历史备份记录清除掉（delete backup），却一直报错。

问题：

• 拆卸老磁带库简单粗暴，没有考虑历史备份的数据问题，历史备份已不可用；所以需要手动清理rman里的历史备份记录；

• 希望以不破坏数据库的正常运行为前提，也不考虑以前的历史备份情况下，清除历史备份信息；

• 简单来说，就是使list backup命令的结果为空即可；

-- 在RMAN里删除历史备份信息时报错，无法删除，使用以下命令均不行：
RMAN> delete backup;
RMAN> delete backupset;
RMAN> delete noprompt backup;
RMAN> delete obsolete;
RMAN> delete noprompt obsolete;

报错信息：

-- 在执行清理操作时报错如下：
RMAN> delete obsolete;
RMAN retention policy will be applied to the command
RMAN retention policy is set to redundancy 1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of delete command at 10/23/2015 18:04:47
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27211: Failed to load Media Management Library
Additional information: 2

问题排查：

1. 因为备份已不可用，尝试crosscheck

-- 清理历史备份：
RMAN> crosscheck backup;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of crosscheck command at 10/26/2015 09:26:45
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27211: Failed to load Media Management Library
Additional information: 2
​
-- 清理历史归档：
RMAN> crosscheck archivelog all;
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=192 device type=DISK
validation succeeded for archived log
archived log file name=/oracle/archivelog/orcl/1_10_893527443.dbf RECID=15 STAMP=893887221
validation succeeded for archived log
archived log file name=/oracle/archivelog/orcl/1_11_893527443.dbf RECID=16 STAMP=893970058
validation succeeded for archived log
archived log file name=/oracle/archivelog/orcl/1_12_893527443.dbf RECID=17 STAMP=894034825
Crosschecked 3 objects
​
RMAN> delete backup of archivelog all;
released channel: ORA_DISK_1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of delete command at 10/26/2015 09:27:21
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27211: Failed to load Media Management Library
Additional information: 2
-- 同样报错，提示SBT_TAPE通道不可用；

2. 解决SBT_TAPE通道不可用问题

• 因为原有通道已经不存在，所以只能再分配一个虚假的磁带通道：

allocate channel for maintenance device type sbt
parms 'SBT_LIBRARY=oracle.disksbt,ENV=(BACKUP_DIR=/tmp)';
​
-- 然后再执行：
crosscheck backup;
delete backup;
-- 命令成功，最终结果如下：
RMAN> list backupset;
specification does not match any backup in the repository
RMAN> list backup;
specification does not match any backup in the repository

3. 重建新备份

在清理掉不可用备份之后，重建磁盘存储池，修改备份脚本，使用磁盘通道备份，过程不再赘述；

问题解决！