12 Replies Latest reply: Feb 11, 2013 2:00 AM by just a DBA RSS

    Rman, noarchivelog and nologging

    just a DBA
      Hello. Please, explain the following.

      I have level 0 backup. I plan to perform bulk updates. For this I will put database temporarily in noarchivelog mode. Some updates will be even in nologging. After this I will return database to archivelog mode. The question is: can I then perform incremental backups of level 1 that will be based on that level 0 ? Can I use that level 0 for recover database with new incremental backups ?
        • 1. Re: Rman, noarchivelog and nologging
          Hemant K Chitale
          can I then perform incremental backups of level 1 that will be based on that level 0 ?
          Yes.
          Can I use that level 0 for recover database with new incremental backups ?
          Only to a point that is aftetr the first incremental backup.


          This would be a good scenario for you to try and practice. The incremental backups do not require archivelogs between the L0 backup and the beginning of the incremental backup if you do not plan to recover to any point in time in between.

          However, all archivelogs generated while the backups (L0 or Incremental) must be backed up as well.


          Hemant K Chitale
          • 2. Re: Rman, noarchivelog and nologging
            asahide
            Hi,

            RMAN introduction is here..
            <<http://www.terrencemiao.com/Webmail/msg00884.html>>

            HTH,
            • 3. Re: Rman, noarchivelog and nologging
              brunors
              Read the article below. I believe that will help you.


              Rman level 0 incremental backup – why restore needs older backups? <Thread: Rman level 0 incremental backup – why restore needs older backups? >
              http://docs.oracle.com/cd/B19306_01/backup.102/b14192/bkup004.htm 4.4 RMAN Incremental Backups

              Kind regards,
              Bruno Reis.
              www.brunors.com
              • 4. Re: Rman, noarchivelog and nologging
                just a DBA
                Thanks to all for answers.
                Hemant, can you explain this :
                However, all archivelogs generated while the backups (L0 or Incremental) must be backed up as well.
                I checked all L1 backups created for a month and found that all datafiles in L1 backupset have the same SCNs. So, if I apply any L1 to L0, database will be consistent and will not require archivelogs in order to be opened?
                • 5. Re: Rman, noarchivelog and nologging
                  Hemant K Chitale
                  Strictly speaking, you do not require intermediate ArchiveLogs between two backups.

                  You require ArchiveLogs generated while the backup was running.

                  However, it is good to have all the intermediate ArchiveLogs as well --- these will allow you to RECOVER the database to any point between the two backups.


                  Hemant K Chitale
                  • 6. Re: Rman, noarchivelog and nologging
                    Hemant K Chitale
                    Why did I say : "This would be a good scenario for you to try and practice."

                    See : http://hemantoracledba.blogspot.sg/2013/02/backup-and-recovery-with-intermediate.html


                    Hemant K Chitale
                    • 7. Re: Rman, noarchivelog and nologging
                      Mihael
                      I checked all L1 backups created for a month and found that all datafiles in L1 backupset have the same SCNs. So, if I apply any L1 to L0, database will be consistent and will not require archivelogs in order to be opened?
                      Yes, you can open database after applying L1 without applying logs if:

                      1. All datafiles in this L1 has the same Checkpoint SCN, i.e. this L1 has only one backup set.
                      AND
                      2. V$BACKUP_DATAFILE.ABSOLUTE_FUZZY_CHANGE# = 0 for all datafiles in this backup set, i.e. datafiles were not updated during backup.

                      This will be true only for idle systems.
                      • 8. Re: Rman, noarchivelog and nologging
                        just a DBA
                        Why did I say : "This would be a good scenario for you to try and practice."

                        See : http://hemantoracledba.blogspot.sg/2013/02/backup-and-recovery-with-intermediate.html
                        I have tested L1 backup after noarchivelog and it worked! In your blog there is no phrase "incremental level 0". So, appears a question: how to set full backup to be level 0 backup if backup is already made ?
                        • 9. Re: Rman, noarchivelog and nologging
                          just a DBA
                          Mihael wrote:
                          I checked all L1 backups created for a month and found that all datafiles in L1 backupset have the same SCNs. So, if I apply any L1 to L0, database will be consistent and will not require archivelogs in order to be opened?
                          Yes, you can open database after applying L1 without applying logs if:

                          1. All datafiles in this L1 has the same Checkpoint SCN, i.e. this L1 has only one backup set.
                          AND
                          2. V$BACKUP_DATAFILE.ABSOLUTE_FUZZY_CHANGE# = 0 for all datafiles in this backup set, i.e. datafiles were not updated during backup.

                          This will be true only for idle systems.
                          Thanks a lot!
                          • 10. Re: Rman, noarchivelog and nologging
                            Hemant K Chitale
                            how to set full backup to be level 0 backup if backup is already made
                            In the meantime, I have updated my blog post with the same case beginning with an actual L0 backup.


                            Although an L0 backup and a full backup are really the same, for the purpose of an Incremental Backup run subsequently, they are distinct. An Incremental backup command does not recognise a Full Backup as a base for backups -- it does not treat the Full Backup as if it were an L0 backup (although it really is !)


                            I know of no way to convert a Full Backup to an L0 backup. However, the first subsequent Incremental L1 backup will automatically create an L0 backup (so the next Incremental L1 backup after that will be a proper L1 backup).


                            Hemant K Chitale
                            • 11. Re: Rman, noarchivelog and nologging
                              Mihael
                              Strictly speaking, you do not require intermediate ArchiveLogs between two backups.

                              You require ArchiveLogs generated while the backup was running.
                              Hemant,
                              this is not always true. If there are some missing logs between L0 and L1, then you can lose all new datafiles created after L0.

                              corrected: L1 includes new datafiles, archivelogs are not required.

                              Edited by: Mihael on Feb 10, 2013 11:37 PM
                              • 12. Re: Rman, noarchivelog and nologging
                                just a DBA
                                Hemant K Chitale wrote:
                                Although an L0 backup and a full backup are really the same, for the purpose of an Incremental Backup run subsequently, they are distinct. An Incremental backup command does not recognise a Full Backup as a base for backups -- it does not treat the Full Backup as if it were an L0 backup (although it really is !)


                                I know of no way to convert a Full Backup to an L0 backup. However, the first subsequent Incremental L1 backup will automatically create an L0 backup (so the next Incremental L1 backup after that will be a proper L1 backup).
                                Yes, I checked that if even set the same tag for full and level 1 backups, rman will ignore full backup and will create new one. Many thanks !