【轉】怎樣修改Oracle的SID

Hi Tom,

A trivia question for you, what is SID and what is it used for? Would changing it have
any impact on the different instances of the database? And lastly, where can I find out
the SID of my database? I don't seem to able to find it in technet.oracle.com.

Please explain.

Thanks
GoJo.

and we said...The SID is a site identifier. It plus the Oracle_home are hashed together in Unix to
create a unique key name for attaching an SGA. If your Oracle_sid or Oracle_home is not
set correctly, you'll get "oracle not available" since we cannot attach to a shared
memory segment that is identified by magic key. On NT, we don't use shared memory but
the SID is still important. We can have more then 1 database on the same oracle home so
we need a way to id them.

Changing it harder then it looks. I know you are on unix, so here are the steps for
changing it (or the database name) under Unix - they are different on NT.

How to find the sid -- "select instance from v$thread" will do that.

PURPOSE
This entry describes how to find and change the "db_name" for a database, or the
ORACLE_SID for an instance, without recreating the database.

SCOPE & APPLICATION
For DBAs requiring to either find or change the db_name or ORACLE_SID.

To find the current DB_NAME and ORACLE_SID:
===========================================

Query the views v$database and v$thread.

V$DATABASE gives DB_NAME
V$THREAD gives ORACLE_SID

If ORACLE_SID = DB_SID and db_name = DBNAME:

To find the current value of ORACLE_SID:

SVRMGR> select instance from v$thread;

INSTANCE
----------------
DB_SID

To find the current value of DB_NAME:

SVRMGR> select name from v$database;

NAME
---------
DBNAME


Modifying a database to run under a new ORACLE_SID:
===================================================

1. Shutdown the instance

2. Backup all control, redo, and data files.

3. Go through the .profile, .cshrc, .login, oratab, tnsnames.ora, (for SQL*Net version
2), and redefine the ORACLE_SID environment variable to a new value.

For example, search through disks and do a grep ORACLE_SID *

4. Change locations to the "dbs" directory

% cd $ORACLE_HOME/dbs

and rename the following files:

o init.ora (or use pfile to point to the init file.)
o control file(s). This is optional if you do not rename any
of the controlfiles, and the control_files parameter is used.
The "control_files" parameter is set in the "init.ora" file or in a file it
references with the ifile parameter. Make sure that the control_files parameter does
not point to old file names, if you have renamed them.
o "crdb.sql" & "crdb2.sql", This is optional. These are only used at
database creation.

5. Change locations to the "rdbms/admin" directory

% cd $ORACLE_HOME/rdbms/admin

and rename the file:

o startup.sql. This is optional. On some platforms, this file may be in the
"$ORACLE_HOME/rdbms/install" directory. Make sure that the contents of this file do not
reference old init.ora files that have been renamed. This file simplifies the
"startup exclusive" process to start your database.

6. To rename the database files and redo log files, you would follow the instructions
in <9560.1>.

7. Change the ORACLE_SID environment variable to the new value.

8. Check in the "$ORACLE_HOME/dbs" directory to see if the password file has been
enabled. If enabled, the file "orapw" will exist and a new password file for
the new SID must be created (renaming the old file will not work). If "orapw"
does not exist, skip to step 9. To create a new password file, issue the following
command as oracle owner:

orapwd file=orapw password=?? entries=permission to start the database instance>

9. Start up the database and verify that it works. Once you have done this, shutdown
the database and take a final backup of all control, redo, and data files.

10. When the instance is started, the control file is updated with the current
ORACLE_SID.


Changing the "db_name" for a Database:
======================================

1. Login to Server Manager

% svrmgrl
SVRMGR> connect internal

2. Type

SVRMGR> alter system switch logfile;

to force a checkpoint.

3. Type

SVRMGR> alter database backup controlfile to trace resetlogs;

This will create a trace file containing the "CREATE CONTROLFILE"
command to recreate the controlfile in its current form.

4. Shutdown the database and exit SVRMGR

SVRMGR> shutdown

SVRMGR> exit

The database must be shutdown with SHUTDOWN NORMAL or SHUTDOWN IMMEDIATE. It must not
be shutdown abnormally using SHUTDOWN ABORT.

5. Change locations to the directory where your trace files are located. They are
usually in the "$ORACLE_HOME/rdbms/log" directory. If "user_dump_dest" is set in the
"init.ora" file, then go to the directory listed in the "user_dump_dest" variable.
The trace file will have the form. "ora_NNNN.trc with NNNN being a number.

6. Get the "CREATE CONTROLFILE" command from the trace file and put it in a new file
called something like "ccf.sql".

7. Edit the "ccf.sql" file

FROM: CREATE CONTROLFILE REUSE DATABASE "olddbname" NORESETLOGS ...
TO: CREATE CONTROLFILE set DATABASE "newdbname" RESETLOGS ...

FROM:
# Recovery is required if any of the datafiles are restored backups,
# or if the last shutdown was not normal or immediate.
RECOVER DATABASE USING BACKUP CONTROLFILE
TO:
# Recovery is required if any of the datafiles are restored backups,
# or if the last shutdown was not normal or immediate.
# RECOVER DATABASE USING BACKUP CONTROLFILE

8. Save and exit the "ccf.sql" file

9. Rename the old control files for backup purposes and so that they do not exist when
creating the new ones.

10. Edit the "init.ora" file so that db_name="newdb_name" .

11. Login to Server Manager

% svrmgrl
SVRMGR> connect internal

12. Run the "ccf.sql" script.

SVRMGR> @ccf

This will issue a startup nomount, and then recreate the controlfile.

If, at this point, you receive the error that a file needs media recovery, the
database was not shutdown normally as specified in step 4. You can try recovering the
database using the redo in the current logfile, by issuing:

SVRMGRL> recover database using backup controlfile;

This will prompt for an archived redologfile. It may be possible to open the
database after applying the current logfile. BUT this is not guaranteed. If, after
applying the current logfile, the database will not open then it is highly likely that
the operation must be restarted having shutdown the database normally.

To apply the necessary redo, you need to check the online logfiles and apply the one
with the same sequence number as reported in the message. This usually is the logfile
with status=CURRENT.

To find a list of the online logfiles:

SVRMGR> select group#, seq#, status from v$log;
GROUP# SEQUENCE# STATUS
---------- --------- ----------------
1 123 CURRENT <== this redo needs to be applied
2 124 INACTIVE
3 125 INACTIVE
4 126 INACTIVE
5 127 INACTIVE
6 128 INACTIVE
7 129 INACTIVE

7 rows selected.

SVRMGR> select member
from v$logfile
where GROUP# = 1;

Member
------------------------------------
/u02/oradata/V815/redoV81501.log

The last command in ccf.sql should be:

SVRMGR> alter database open resetlogs;

13. You may also need to change the global database name:

alter database rename global_name to .

See <1018634.102> for further detail.

14. Make sure the database is working.

15. Shutdown and backup the database.