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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Change based recovery
Well I am quite de-motivated actually!! but at least it is good to know I was (partially) wrong and that I will feel safer after reading your comments, thanks!
I am really in doubt now, but I remember when we were testing we did recover all datafiles (the ones that are stated in the v$datafile table) from a cold backup except control files and redolog files; we were able to restore the whole database with the commands I wrote down in my first message. If I am still wrong, will you please be kind enough to tell me which are the exact commands needed to recover the whole database from a cold backup if I have no online backups and I lose everything except for the archived logs? can it really be done?
Thank you so much!
Fermin.
-----Mensaje original-----
De: Venu Gopal [mailto:venu.andem_at_wipro.com]
Enviado el: lunes, 11 de agosto de 2003 13:44
Para: Multiple recipients of list ORACLE-L
Asunto: RE: Change based recovery
Fermin,
I don't want to de-motivate you, but I really doubt whether your backup strategy really works. The command that you have mentioned below will NOT do a complete recovery as it's a cold backup.
As for your questions:
1) You can recover your entire database in either case (Cold or Hot), If you have your archive logs.
Difference being, You have recreate your control file if it's a cold DB backup and recover the DB using 'BACKUP CONTROL FILE' option. 2) Lets look at it the other way; you do NOT need any downtime for Hot backups while you need downtime for Cold backups. Downtime could be very expensive depending on the type of database. Secondly, you can take a hot backup very frequently as it does not involve any downtime. Recent backup means less recovery is required and less time to bring up the database.
Let me know if you need anymore info.
Cheers!
Venu
-----Original Message-----
Fermin Bernaus
Sent: Monday, August 11, 2003 4:54 PM
To: Multiple recipients of list ORACLE-L
I've been reading your messages with much interest. I have some experience with database administration and I have done many tests, but I've not tried what I am going to expose in this message, maybe you can help. We do cold backups on a regular basis (every weekend) then just backup the archive log every day, then delete them every time a new cold backup is done. We have tested it and if all database files (parameters file, datafiles, control files) except for one control file and the archived logs were lost we could recover the entire database issuing the following commands after restoring all missing files and mounting the database:
SET AUTORECOVERY ON
RECOVER DATABASE
ALTER DATABASE OPEN
My questions are:
1 - Could a complete restore be done even if we lost ALL control files? can we recover the entire database from a cold backup provided we have all archived logs until the failure time? 2 - If the answer is yes, what is the advantage of doing on-line backups of datafiles and control files?
Thanks for your answers, I always learn so much from this list!!
Fermin.
-----Mensaje original-----
De: Hand, Michael T [mailto:HANDM_at_polaroid.com]
Enviado el: viernes, 08 de agosto de 2003 18:10
Para: Multiple recipients of list ORACLE-L
Asunto: RE: Change based recovery
Lisa,
The 3rd option (besides shuting down source database and using a controlfile trace) is to "alter database backup controlfile to 'filename'; ", use this file, then proceed with the recovery as Venu suggests. I've used this method on a hot backup to roll the database forward. Also, don't bother restoring the redo logs as you will be overwriting / recreating them with the "alter database open resetlogs". One more thing I noticed. Your until change number looks to me like an archive sequence number rather than the SCN it needs to be. Hope this helps.
Mike Hand
-----Original Message-----
Sent: Thursday, August 07, 2003 8:21 AM
To: Multiple recipients of list ORACLE-L
Hi Guys and Gals,
We are currently doing some testing to enable us to move our production database from one unix box to another.
We are running a 7.3.4 db in archivelog mode. The approach that management want to use is to restore the database on the new server from a backup and then roll it forward using the archived redo logs.
I have a full cold back up from last Friday. I have restored the datafiles, controlfiles and redo logs onto our test server from the backup tape, and then ftp'd the archived logs over.
I then do -
SVRMGR> startup mount
ORACLE instance started.
Total System Global Area 258304260 bytes Fixed Size 45092 bytes Variable Size 126925024 bytes Database Buffers 131072000 bytes Redo Buffers 262144 bytesDatabase mounted.
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Fermin Bernaus INET: fbernaus_at_sammic.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting servicesReceived on Mon Aug 11 2003 - 07:34:22 CDT
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