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This article introduces the relevant knowledge of "how to restore the mistakenly deleted oracle data files under linux". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Scenario description: the data file is deleted at the operating system level (/ oracle/oradata/ora10g/system1.dbf), and the database does not crash, still in the open state.

Principle: in the Linux operating system, if a file is deleted from the operating system level, the process that opened the file before still holds the corresponding file handle, the file it points to can still read and write, and the file descriptor of the file can be obtained from the / proc directory. If you close the database, the handle is lost.

The recovery steps are as follows:

1. Check the process PID of dbwr

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

2bot dbwr opens the handle to all data files.

Can be found in the proc directory, the directory name is the process PID,fd represents the file descriptor

As shown in the figure:

[root@localhost fd] # ls-l

Total 0

Lrwx- 1 oracle dba 64 Jan 3 18:35 23-> / oracle/oradata/ora10g/example01.dbf

Lrwx- 1 oracle dba 64 Jan 3 18:35 24-> / oracle/oradata/ora10g/test01.dbf

Lrwx- 1 oracle dba 64 Jan 3 18 Jan 3525-> / oracle/oradata/ora10g/app1.dbf (deleted)

Lrwx- 1 oracle dba 64 Jan 3 18:35 26-> / oracle/oradata/ora10g/perfstat.dbf

Lrwx- 1 oracle dba 64 Jan 3 18:35 27-> / oracle/oradata/ora10g/test02.dbf

Lrwx- 1 oracle dba 64 Jan 3 18:35 28-> / oracle/oradata/ora10g/temp01.dbf

Lrwx- 1 oracle dba 64 Jan 3 18:35 29-> / oracle/oradata/ora10g/temp02.dbf

The red part means that the app1 file has been deleted.

3. Copy the handle directly to the location of the original data file

Host cp / proc/3591/fd/25/oracle/oradata/ora10g/system1.dbf

4, restore the file

Alter database datafile 7 offline

Recover datafile 7

Alter database datafile 7 online

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