How to recover files that were accidentally deleted under Linux

Today, a customer's database accidentally deleted the entire directory of data files, operating system level deletion, but fortunately the database did not crash, still in the open state, the customer found a problem, help us, and finally fully recover all the data files.

Under Linux, a general demonstration of the recovery process, the recovery steps and the database version is not much of a relationship, and the operating system will vary.

1. Delete data files in the users table space directly when the database is open.

Sql> select name from V$datafile;

NAME

--------------------------------------------------------------------------------

/app/oracle/oradata/orcl/datafile/o1_mf_system_555wqbnk_.dbf

/app/oracle/oradata/orcl/datafile/o1_mf_undotbs1_555wqxgl_.dbf

/app/oracle/oradata/orcl/datafile/o1_mf_sysaux_555wr5p6_.dbf

/app/oracle/oradata/orcl/datafile/o1_mf_users_555wrj4o_.dbf

Sql> Host RM/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_USERS_555WRJ4O_.DBF

2. Try to create a table in the Users table space and start an error.

Sql> CREATE TABLE T tablespace users as SELECT * from dual;

CREATE TABLE T tablespace users as SELECT * from dual

*

ERROR at line 1:

Ora-01116:error in opening database file 4

Ora-01110:data File 4:

'/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_USERS_555WRJ4O_.DBF '

Ora-27041:unable to open File

Linux error:2: No such file or directory

Additional Information:3

Similar information can also be seen in the alarm log.

Mon Dec 21:48:17 CST 2011

Errors in FILE/APP/ORACLE/ADMIN/ORCL/BDUMP/ORCL_M000_3897.TRC:

Ora-01116:error in opening database file 4

Ora-01110:data file 4: '/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_USERS_555WRJ4O_.DBF '

Ora-27041:unable to open File

Linux error:2: No such file or directory

Additional Information:3

3. Check the DBWR process PID

$ ps-ef|grep dbw0|grep-v grep

Oracle 2879 1 0 21:38? 00:00:00 ORA_DBW0_ORCL

This paper url:http://www.bianceng.cn/os/linux/201410/45614.htm

4. DBWR will open the handle to all data files. As can be found in the proc directory, the directory name is a process PID,FD representation of the file descriptor.

$ cd/proc/2879/fd

$ ls-l

Total 0

LR-X------1 Oracle DBA 21:50 0->/dev/null

LR-X------1 Oracle DBA 21:50 1->/dev/null

LR-X------1 Oracle DBA 21:50->/dev/zero

LR-X------1 Oracle DBA 21:50->/dev/zero

LR-X------1 Oracle DBA 21:50->/APP/ORACLE/PRODUCT/10.2.0/DB_1/RDBMS/MESG/ORAUS.MSB

LRWX------1 Oracle DBA 21:50->/app/oracle/product/10.2.0/db_1/dbs/hc_orcl.dat

LRWX------1 Oracle DBA 21:50->/APP/ORACLE/PRODUCT/10.2.0/DB_1/DBS/LKORCL

LRWX------1 Oracle DBA 21:50->/APP/ORACLE/ORADATA/ORCL/CONTROLFILE/O1_MF_555WQ3NG_.CTL

LRWX------1 Oracle DBA 21:50->/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_SYSTEM_555WQBNK_.DBF

LRWX------1 Oracle DBA 21:50->/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_UNDOTBS1_555WQXGL_.DBF

LRWX------1 Oracle DBA 21:50->/APP/ORACLE/ORADATA/ORCL/DATAFILE/O1_MF_SYSAUX_555WR5P6_.DBF

LRWX------1 Oracle DBA 21:50->/app/oracle/oradata/orcl/datafile/o1_mf_users_555wrj4o_.dbf (Deleted)

LR-X------1 Oracle DBA 21:50 2->/dev/null

LRWX------1 Oracle DBA 21:50->/app/oracle/oradata/orcl/datafile/o1_mf_temp_555wrbnz_.tmp

LR-X------1 Oracle DBA 21:50->/APP/ORACLE/PRODUCT/10.2.0/DB_1/RDBMS/MESG/ORAUS.MSB

LR-X------1 Oracle DBA 21:50 3->/dev/null

LR-X------1 Oracle DBA 21:50 4->/dev/null