1. Get rid of all advertisements and get unlimited access to documents by upgrading to Premium Membership. Upgrade to Premium Now and also get a Premium Badge!

Oracle 10g Instance Recovery and Checkpoint

Discussion in 'General' started by viral, Aug 10, 2011.

  1. viral

    viral Active Member

    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    55
    Hi!
    This time I have some of the issue with the Oracle 10g's instance recovery. At the time of Instance Recovery, SMON is the background process that performs the instance recovery....but
    1)How will Oracle come to know if there is a need for Instance Recovery???
    2)What are the files that will be read so that the Instance Recovery will be performed???
    3)What are the events that cause Checkpoint???
    4)What happens after the checkpoint occurs???


    If possible please give the answer of the second question till tomorrow???
     
  2. zargon

    zargon Community Moderator Forum Guru

    Messages:
    2,347
    Likes Received:
    348
    Trophy Points:
    1,430
    Location:
    Aurora, CO
    1)How will Oracle come to know if there is a need for Instance Recovery???

    The last SCN for each data file is recorded in the controlfile and the data file header (see #4 for how this is done); Oracle checks the file headers against the header information in the controlfile and if an older SCN is recorded in a data file header that file needs recovery. This is done for all data files in the database.

    2)What are the files that will be read so that the Instance Recovery will be performed???

    Are you asking which files supply the information/data for recovery? The redo logs/archivelogs are used to perform recovery.

    3)What are the events that cause Checkpoint???

    Commits, usually. Occasionally the log_checkpoint_interval parameter s set to a non-zero value causing additional checkpoints to occur at the scheduled interval.

    4)What happens after the checkpoint occurs???

    The data for the activity is written to the checkpoint data structure which records SCN information for the transaction in the controlfile and in the data file headers. When these checkpoints don't match recovery is needed; see answer for question #1.