9 Replies Latest reply: Jan 29, 2013 12:47 AM by Mihael RSS

    Incomplete Recovery - Clarification

    Arun Natarajan-OC
      Hi Friends,

      I am using Oracle 11g.

      I lost my control files and dbf files but i had redologs un disturbed.

      so i restored control files and datafiles from rman backup , performed recovery with archived logs and the existing Redo log. so i didn't receieve sequence error . The Recovery was perfect since i had redo logs un affected.

      But when i try to open database it allows me to do only with resetlogs.

      so it means , though i could apply all my complete transactions (datafiles + archived logs+ redo logs) am i performing an incomplete recovery?

      Please explain.


      As per my understanding from the above the Recovery is Incomplete if


      1) If control file is restored / recreated (though you have redo logs available and apply redo logs)

      (or)

      2) If redo log is not applied (because it is missing) and could apply only dtafiles + archived logs (you may lose transaction from redologs)

      (or)

      3) Perform Point in Time recovery (obviously we lose transactions)


      Please confirm

      Regards,
      DB
        • 1. Re: Incomplete Recovery - Clarification
          Hemant K Chitale
          performed recovery with archived logs and the existing Redo log
          What command did you issue for the Recovery ? Was it from the RMAN command prompt or SQL command prompt ?


          Hemant K Chitale
          • 2. Re: Incomplete Recovery - Clarification
            Lukas Bica-Oracle
            Hello,
            you used this command for recovery?
            recover database until cancel using backup controlfile;
            if you are restoring controlfile and recovering from it, you don't know last SCN. And if you are applying archive logs and redo logs, database can't verify that you have presented all redo/archive logs. In that case database need to do resetlogs.
            Incomplete recovery in case of lost of redologs, archive logs or point in time recovery are clearly incomplete because you don't have all information from logs and you are going back to history in database.

            Lukas
            • 3. Re: Incomplete Recovery - Clarification
              AJ
              When you restore the controlfile from backup you always have to open the database with resetlogs (even when you're not restoring any data files).

              (edit: additional info)
              On the other hand: If you had a trace of your controlfile (alter database backup controlfile to trace) you could have re-created the controlfile with NORESETLOG option (since your online redo logs were intact) and opened the database without the resetlogs option after complete recovery.

              Edited by: AJ on 18.jan.2013 06:45

              Edited by: AJ on 18.jan.2013 06:49
              • 4. Re: Incomplete Recovery - Clarification
                Arun Natarajan-OC
                Hi AJ / Friends,

                Thanks for the info and it clarified the question.

                But consider this scenario , I am having Redo Logs so in that case can i perform control file restore from RMAN backup (not control Trace File) and perform complete recovery (which i can do if i have redo logs and i create control file using Trace) .

                If so , then please let me know the steps.

                If not then my question is how come RMAN Control file backup is inferior to the manually created control file (using Trace file)?

                Regards,
                DB
                • 5. Re: Incomplete Recovery - Clarification
                  Hemant K Chitale
                  Technically, if you RESTORE a Controlfile, it is a BACKUP CONTROLFILE. You need to issue a RESETLOGS after the RECOVERy.

                  See Performing Recovery with a Backup Control File at http://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmadvre.htm#i1008870


                  Hemant K Chitale
                  • 6. Re: Incomplete Recovery - Clarification
                    Mihael
                    If you restore control file from backup, Oracle do not know how many logs you have even if they are not lost - you could add more redo log groups to thread or even add new thread. So you must use "resetlogs".
                    If you create new controlfile, then you specify exactly what redo logs you have, and if they are present, "resetlogs" is not needed.
                    • 7. Re: Incomplete Recovery - Clarification
                      Arun Natarajan-OC
                      Hi Mihael / Friends,

                      Thanks , assuming i haven't made any changes to Redo Log groups , in that case can use RMAN to restore control file and perform complete recovery (noresetlog)? Any option is available?

                      (or) irrespective of whether changes made (or) not to redologs if control file is restored from RMAN then it is mandataory to perform resetlog?


                      If option 2 is correct then i believe,

                      Though we use RMAN backup as best method in many ways compared to OS backup , for control file restoration alone it's not good to use RMAN restore as this will end up in new incarnation of database and will invalidate all my old backup's , so it's best to use the control file trace to recreate control file and perform complete recovery. Is this true?

                      what will happen to my RMAN old backup's if i recreate control file and perform noresetlog / restore control file from RMAN and perform resetlogs? will it be registered (or) not registered in control file in both cases.

                      Regards,
                      DB
                      • 8. Re: Incomplete Recovery - Clarification
                        Hemant K Chitale
                        Since 10g, Oracle allows Recovery through a RESETLOGS, even if the incarnation changes. One key feature of this is that ArchiveLogs have %r (which is the resetlogs ID) as part of the file name.


                        If you do a CREATE CONTROLFILE all information about backups that were present in the controlfile are "lost". If you are running without a Recovery Catalog, you lose information about backups. If you are running with a Recovery Catalog, you have the information in the Recovery Catalog but you cannot "synch" the data from the Recovery Catalog to the (newly created) controlfile.


                        Hemant K Chitale
                        • 9. Re: Incomplete Recovery - Clarification
                          Mihael
                          If you create new controlfile, you can register all backups and archivelogs with rman "catalog" command. The command allows to register single backup or log and also to specify start directory for backups or even full FRA.