Results 1 to 3 of 3
  1. #1
    Join Date
    Dec 2003
    Location
    India
    Posts
    33

    Cool Unanswered: high redo generation rate

    Why, when I'm taking a hot back up, the redolog generation is very high ? Please explain in detail...

    thanks
    Papps...

  2. #2
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    It is because when in archive mode and NOT doing hot backups,
    only the changed information within a block is written to redo logfile.
    When in archive mode & the tablespace has been placed into backup mode the whole block is written to the redo logfile; regardless of the number of bytes within the block that changed.

  3. #3
    Join Date
    Apr 2003
    Location
    Minneapolis, MN
    Posts
    273
    When you take the Hot Backup using ALTER TABLESPACE <name> BEGIN BACKUP command, Oracle perform checkpoint on the data file(s) of the this tablespace. It stamps the SCN on the header of each datafiles. Now every DML operatons are performed in the same way but Oracle has to write this Extra information about these blocks (required for recovery) in the Redo log files. It writes this untill you execute ALTER TABLESPACE <name> END BACKUP.
    So this is the reson It generates more redo in the log files.

    So use RMAN.
    Bhavin

    MS Computer Science
    OCP DBA 9i/8i

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •