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4 Replies Latest reply: Jan 19, 2013 7:33 AM by EdStevens RSS

Obsolete backups - recovery window

Neo-b Newbie
Currently Being Moderated
Hello All,

I am using Oracle RAC 11g R2.

I am having Level 0 backups on Saturday at 1:00 am and cumulative level 1 backups on the other days of the week. As described below:
12    13     14     15     16     17     18     19     20     21     22      23     24     25
S     SU     MO     TU     WE     TH     FR      S     SU     MO     TU     WE     TH     FR
0     1      1      1      1       1      1      0     1      1      1       1       1      1
My recover window is for 3 days.

Today is Saturday 19th, So for sure in my fast recovery area I will have 2 level 0 backups since I need to recover my database till Wednesday 16th which is a level 1 backup, then I need the level 0 backup of previous Saturday 12th. So this backup will not be marked as obsolete.

My question since i am have cumulative level 1 backups, should not level 1 backups of Sunday 13th , Monday 14th and Tuesday 15th marked as obsolete?

I reviewed my RMAN backup logs and some of the Level 1 backups of Sunday, Monday and Tuesday were marked as obsolete, but not all Level 1 backup sets were marked as obsolete for these days, neither the Archive logs backups was marked as obsolete.

Regards,
  • 1. Re: Obsolete backups - recovery window
    mseberg Guru
    Currently Being Moderated
    Hello;

    1 backups of Sunday 13th , Monday 14th and Tuesday 15th marked as obsolete?

    If I understand the information given then the answer is no.

    I think of level 1 backups as pieces or additions to level 0 backups. Without the level 0 backup they are worthless.

    So they are not obsolete until the level 0 they are based on is.

    This may help :

    http://www.visi.com/~mseberg/rman/obsolete_backups.html

    Best Regards

    mseberg
  • 2. Re: Obsolete backups - recovery window
    Neo-b Newbie
    Currently Being Moderated
    I am reviewing my logs and some of the level 1 backups of Sunday, Monday and Tuesday are marked obsolete while the others are not, till not I am still seeing some level 1 backups in my FRA for day 13.
    I am not able to understand the criteria marking level 1 backups as obsolete, can it be something related to the backups of the system table spaces?

    and even the backup of the archive logs of 13, 14, and 15 are not marked as obsolete yet. while logically I will not use it in case i want to recover my database, since i am using cumulative level 1 backups.

    All the documentation i have read it, do not mention if there is any difference on how recovery window deals with cumulative or differential level 1 backups.

    Regards,
  • 3. Re: Obsolete backups - recovery window
    mseberg Guru
    Currently Being Moderated
    RMAN holds all level 1 backups that are related to Level 0 backup.

    When you make a backup that make the level 0 obsolete are related level 1 backups are then obsolete.


    Remember level 1 backups are junk if you don't have a level 0 backup.

    Best Regards

    mseberg
  • 4. Re: Obsolete backups - recovery window
    EdStevens Guru
    Currently Being Moderated
    291223 wrote:
    RMAN holds all level 1 backups that are related to Level 0 backup.

    When you make a backup that make the level 0 obsolete are related level 1 backups are then obsolete.


    Remember level 1 backups are junk if you don't have a level 0 backup.

    Best Regards

    mseberg
    Hmm. I'd never thought of this, but if I understand the OP correctly, consider:

    Day 1 - level 0
    Day 2 - level 1 cumulative - all changes since day 1
    Day 3 - level 1 cumulative - all changes since day 1 -- which would include all changes covered in Day 2 backup.

    So, at this point, since day 3 includes what day 2 includes, why couldn't day 2 be considered obsolete? If rman needs to recover the changes that were recorded in the Day 2 backup, they are available in the day 2.

    No, as I write it, I think it through a bit more and see the issue.

    On day 2 rman finds block 'xyz' changed from when it was backed up on Day 1, so backs it up. Fine.
    On Day 3 rman will obviously again find that block 'xyz' changed from when it was backed up on Day 1, and so will back it up again. However, block 'xyz' could also have been changed since the Day 2 backup, making the day 3 version of the block the second version since Day 1 - different from the version in the Day 2 backup. If we were to make the Day 2 backup obsolete we would have lost the ability to use Day 2 backup as part of a PIT recovery and would be forced to use archivelogs back to the Day one backup. And that would make all of our Inc 1 cumulative backups pretty much pointless for anything less than a full recovery.

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