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Why oracle instance doesn't shutdwon after deleting system datafile? [message #642537]

Mon, 14 September 2015 04:04

anyoneokay
Messages: 10
Registered: September 2007

Junior Member

Hi all,

As oracle said, In the archivelog mode, if Datafiles in the SYSTEM tablespace or datafiles with active undo segments is damaged, then the oracle database will shutdown.

But I have a experience on oracle 10g, when I delete or move system datafile, I found the instance still run well, although you can see there are some error message from alert log.

Can anybody tell me why the database won't shutdown after deleting system datafile? any suggestion will be appreciated.

Some testing code is following
-------------------------------------------------------------------------------

[oracle@oraserver ORADB]$ mv system01.dbf /tmp/system01.dbf
[oracle@oraserver ORADB]$ mv undotbs01.dbf /tmp/undotbs01.dbf
[oracle@oraserver ORADB]$ ll
total 833800
drwxr-xr-x 2 oracle oinstall      4096 Sep 14 15:59 archive
-rw-r----- 1 oracle oinstall   7094272 Sep 14 16:23 control01.ctl
-rw-r----- 1 oracle oinstall   7094272 Sep 14 16:23 control02.ctl
-rw-r----- 1 oracle oinstall   7094272 Sep 14 16:23 control03.ctl
-rw-r----- 1 oracle oinstall 104865792 Sep 14 16:10 example01.dbf
-rw-r--r-- 1 oracle oinstall  83886080 Sep 14 11:11 new01.dbf
-rw-r----- 1 oracle oinstall  52429312 Sep 14 15:59 redo01.log
-rw-r----- 1 oracle oinstall  52429312 Sep 14 16:23 redo02.log
-rw-r----- 1 oracle oinstall  52429312 Sep 14 15:59 redo03.log
-rw-r----- 1 oracle oinstall 356524032 Sep 14 16:23 sysaux01.dbf
-rw-r----- 1 oracle oinstall  20979712 Sep 12 06:00 temp01.dbf
-rw-r----- 1 oracle oinstall 104865792 Sep 14 16:10 test01.dbf
-rw-r----- 1 oracle oinstall   5251072 Sep 14 16:10 users01.dbf

SQL> select instance_name, status from v$instance;

INSTANCE_NAME     STATUS
---------------- -------
ORADB         OPEN

SQL> select name, status from v$datafile;

NAME                           STATUS
-------------------------------------------------- -------
/usr/oradata/ORADB/system01.dbf            SYSTEM
/usr/oradata/ORADB/undotbs01.dbf           ONLINE
/usr/oradata/ORADB/sysaux01.dbf            ONLINE
/usr/oradata/ORADB/users01.dbf               ONLINE
/usr/oradata/ORADB/example01.dbf           ONLINE
/usr/oradata/ORADB/test01.dbf               ONLINE

6 rows selected.

SQL> select * from test.date_log where rownum<5;

CURTIME
-------------------
2015-09-02 16:19:28
2015-09-02 16:19:28
2015-09-02 16:20:06
2015-09-02 17:53:15

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Re: Why oracle instance doesn't shutdwon after deleting system datafile? [message #642540 is a reply to message #642537]

Mon, 14 September 2015 04:17

John Watson
Messages: 8960
Registered: January 2010
Location: Global Village

Senior Member

When you remove a file with rm, you aren't deleting the file: you are only removing the directory entry. Same with mv, you aren't changing the file itself. So any process that has already opened a handle on the file can continue to use it.

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Re: Why oracle instance doesn't shutdwon after deleting system datafile? [message #642575 is a reply to message #642540]

Mon, 14 September 2015 13:42

anyoneokay
Messages: 10
Registered: September 2007

Junior Member

I got it, thank you very much for your reply, unix is so amazing.

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