利用Linux的特性恢复误删的数据文件
原文地址：http://www.itpub.net/thread-1044449-1-2.html
帖子中提到如下场景：Oracle on Linux的环境，在没有shutdown数据库的情况下误删数据文件system01.dbf。对于有完好rman备份或者Data Guard的情况下，神马都是浮云，但古语有云“屋漏偏逢连夜雨，船迟又遇打头风”，祸不单行的事情海了去，对于nobackup有什么好办法呢？
少说废话，直接上处理过程：
首先是模拟出这个囧境：
[ora11g@test06 ~]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.2.0 Production on Thu Feb 10 15:43:36 2011 Copyright (c) 1982, 2010, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> select name from v$datafile; NAME -------------------------------------------------------------------------------- /u02/oradata/ORCL/system01.dbf /u02/oradata/ORCL/sysaux01.dbf /u02/oradata/ORCL/undotbs01.dbf /u02/oradata/ORCL/users01.dbf SQL> ! [ora11g@test06 ~]$ ll /u02/oradata/ORCL/system01.dbf -rw-r----- 1 ora11g oradba 765468672 Feb 10 15:44 /u02/oradata/ORCL/system01.dbf [ora11g@test06 ~]$ rm -rf /u02/oradata/ORCL/system01.dbf [ora11g@test06 ~]$ ll /u02/oradata/ORCL/system01.dbf ls: /u02/oradata/ORCL/system01.dbf: No such file or directory [ora11g@test06 ~]$ SQL> connect scott/tiger ERROR: ORA-00604: error occurred at recursive SQL level 1 ORA-01116: error in opening database file 1 ORA-01110: data file 1: '/u02/oradata/ORCL/system01.dbf' ORA-27041: unable to open file Linux-x86_64 Error: 2: No such file or directory Additional information: 3 Warning: You are no longer connected to ORACLE.
数据文件system01.dbf让俺“误”删了，有后悔药可以吃吗？
先找出 db writer 进程，该进程肯定会写数据文件的，也可以通过lsof命令找出打开system01.dbf的所有进程。
[ora11g@test06 ~]$ ps -ef | grep ora_db ora11g 24861 1 0 Jan24 ? 00:00:00 ora_dbrm_ORA11G ora11g 24867 1 0 Jan24 ? 00:00:28 ora_dbw0_ORA11G ora11g 32637 32587 0 15:45 pts/3 00:00:00 grep ora_db
进程号是 24867
[ora11g@test06 ~]$ cd /proc/24867/fd/ [ora11g@test06 fd]$ ll total 0 lr-x------ 1 ora11g oradba 64 Feb 10 15:33 0 -> /dev/null l-wx------ 1 ora11g oradba 64 Feb 10 15:33 1 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 10 -> /u01/app/ora11g/product/11.2.0.2/db_1/rdbms/mesg/oraus.msb lr-x------ 1 ora11g oradba 64 Feb 10 15:33 11 -> /proc/24867/fd lr-x------ 1 ora11g oradba 64 Feb 10 15:33 12 -> /dev/zero lr-x------ 1 ora11g oradba 64 Feb 10 15:33 13 -> /dev/zero lrwx------ 1 ora11g oradba 64 Feb 10 15:33 14 -> /u01/app/ora11g/product/11.2.0.2/db_1/dbs/hc_ORA11G.dat lr-x------ 1 ora11g oradba 64 Feb 10 15:33 15 -> /u01/app/ora11g/product/11.2.0.2/db_1/network/mesg/nlus.msb l-wx------ 1 ora11g oradba 64 Feb 10 15:33 16 -> /u01/app/ora11g/product/11.2.0.2/db_1/network/log/sqlnet.log lr-x------ 1 ora11g oradba 64 Feb 10 15:33 17 -> /dev/zero lrwx------ 1 ora11g oradba 64 Feb 10 15:33 18 -> /u01/app/ora11g/product/11.2.0.2/db_1/dbs/hc_ORA11G.dat lrwx------ 1 ora11g oradba 64 Feb 10 15:33 19 -> /u01/app/ora11g/product/11.2.0.2/db_1/dbs/lkORCL l-wx------ 1 ora11g oradba 64 Feb 10 15:33 2 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 22 -> /u01/app/ora11g/product/11.2.0.2/db_1/rdbms/mesg/oraus.msb lrwx------ 1 ora11g oradba 64 Feb 10 15:33 256 -> /u02/oradata/ORCL/control01.ctl lrwx------ 1 ora11g oradba 64 Feb 10 15:33 257 -> /u01/app/ora11g/fast_recovery_area/ORCL/control02.ctl lrwx------ 1 ora11g oradba 64 Feb 10 15:33 258 -> /u02/oradata/ORCL/system01.dbf (deleted) lrwx------ 1 ora11g oradba 64 Feb 10 15:33 259 -> /u02/oradata/ORCL/sysaux01.dbf lrwx------ 1 ora11g oradba 64 Feb 10 15:33 260 -> /u02/oradata/ORCL/undotbs01.dbf lrwx------ 1 ora11g oradba 64 Feb 10 15:33 261 -> /u02/oradata/ORCL/users01.dbf lrwx------ 1 ora11g oradba 64 Feb 10 15:33 262 -> /u02/oradata/ORCL/temp01.dbf lr-x------ 1 ora11g oradba 64 Feb 10 15:33 3 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 4 -> /dev/null lrwx------ 1 ora11g oradba 64 Feb 10 15:33 5 -> /u01/app/ora11g/product/11.2.0.2/db_1/dbs/hc_ORA11G.dat lr-x------ 1 ora11g oradba 64 Feb 10 15:33 6 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 7 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 8 -> /dev/null lr-x------ 1 ora11g oradba 64 Feb 10 15:33 9 -> /dev/null
可以看到 258 对应的文件是在闪烁的，并且有一个 (deleted) 标记符，先将这个文件复制到另外的目录：
[ora11g@test06 fd]$ cat 258 > /home/ora11g/system01.dbf [ora11g@test06 fd]$ cp /home/ora11g/system01.dbf /u02/oradata/ORCL/system01.dbf
SQL> connect scott/tiger Connected.
貌似没问题了，重启一下数据库看看：
SQL> connect / as sysdba Connected. SQL> SQL> SQL> shutdown immediate ; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ; ORACLE instance started. Total System Global Area 534462464 bytes Fixed Size 2228200 bytes Variable Size 394264600 bytes Database Buffers 130023424 bytes Redo Buffers 7946240 bytes Database mounted. ORA-01113: file 1 needs media recovery ORA-01110: data file 1: '/u02/oradata/ORCL/system01.dbf' SQL> select OPEN_MODE from v$database; OPEN_MODE -------------------- MOUNTED
这个问题不大，system01.dbf相当于没有alter database begin backup那样进行了热备，recover 一下就好：
SQL> recover database ; Media recovery complete. SQL> alter database open ; Database altered. SQL> select OPEN_MODE from v$database; OPEN_MODE -------------------- READ WRITE
搞定。
