Re: Recover database without backup

First off, your colleague really should open a support incident with Oracle Support.

In regard to your question of "is it possible to restore a database using only its datafiles?"
Certainly. The real question is, can the database be recovered. If the database instance was open ...

Ask him to get a backup of all of the files so that they are in another location, prior to attempting to open any of the databases. He may need to make multiple attempts.

I'm going to assume that the databases were in noarchivelog mode.

If he is simply re-creating the configuration of the existing server, and he has all of the required files, this should be straightforward.

If he is missing the controlfiles, it is still possible to re-create a backup controlfile - for each database. Recovery will be required, more that likely just applying what was the current redo log. That information will be in the tail of the alert log for each database.

If he is missing the redo logs, it is still possible for recovery to succeed, provided that the current online redo log for each database is available.

Okay, so he is going to repartition the storage subsystem exactly the same, and put all of the files back in the same directory structure? That will indeed simplfy recovery, as no controlfile paths will need to be renamed in the init.ora file, no online redo logs or datafiles will need to be renamed while the database instance is mounted, prior to performing recovery.

He should install the oracle software as was done before, apply the same patches.

He will then need to create a listener, and add the respective entries into the tnsnames.ora file. A check of the names.default_domain in the sqlnet.ora file should also be done. (lsnrctl start listener)

He will then need to create a password file for each database, if they are missing.
(orapwd.exe)

He will then need to create operating system service for each database.
(oradim) use startmode -m.

if the prior initialization parameter file is in the correct location, or if he specifies it during instance startup ... he should be in business.

C:\> set ORACLE_SID=<mysid1>
C:\> svrmgr30
SVRMGR> connect internal
SVRMGR> startup nomount pfile=c:\orant\database\initMmysid1>.ora

if all goes well ...

SVRMGR> alter database mount;

if all files were available, and in their prior locations ... this should succeed:

SVRMGR> alter database open;

more than likely, at least one of those steps will fail.

have him post the error messages.

Again, he should not operate on the only copy of his files. He should have backup sets of all of the files before performing any sort of recovery.
Oracle Support is his best bet.

hth.

-bdbafh Received on Wed Oct 19 2005 - 20:18:45 CDT