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Junz's avatar
Junz
Level 3
6 years ago

Backup retention period questions

I have a question regarding the backup retention period and restoration. Before i go to my question, please help me to elaborate the scenario that i give below. Let's say my daily incremental backup set to 2 weeks and the weekly full backup set to 3 months.

 Daily backup:
--------------------
 1 Oct 18 ---- retention 2 weeks -----> 15 Oct 18
 2 Oct 18 ---- retention 2 weeks -----> 16 Oct 18
 3 Oct 18 ---- retention 2 weeks -----> 17 Oct 18
 4 Oct 18 ---- retention 2 weeks -----> 18 Oct 18
 5 Oct 18 ---- retention 2 weeks -----> 19 Oct 18
 6 Oct 18 ---- retention 3 months ----> 6 Jan 19

One day on 27 Oct 18, a user report that his file was missing after 2 Oct 18 and request to restore it. Which mean his file still available before 2 Oct or 1 Oct, but the 1 Oct 18 daily backup image already expired. Is the backup engineer still able to find the missing file and restore it?

What my question here is when 6 Oct 18 start a full backup, will it backup the 1 Oct missing file also? or it will only backup the latest state like 5 Oct.

Hope anyone here can understand my question.

Thank you.

8
full backup
incremental backup
Linux
missing file
restoration
retention period
  • Genericus's avatar
    Genericus
    6 years ago

    I highly recommend that every backup admin create a retention document that lists out what you backup, how often, and how long it is kept. This will be all you need to provide for security audits. This is your CYA when someone asks for a restore out of bounds.   So many times I have simply forwarded my doc when requested how longs backups are kept.

    Of course, you also need to update it and ensure it is accurate. 

    It is also leverage to get the customer groups to generate theirs as well...

     

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  • RiaanBadenhorst's avatar
    RiaanBadenhorst
    Level 6
    6 years ago

    You said "What my question here is when 6 Oct 18 start a full backup, will it backup the 1 Oct missing file also? or it will only backup the latest state like 5 Oct."

    Its not possible to backup a file that has been deleted. 

    You said the file "Which mean his file still available before 2 Oct or 1 Oct," which means the file is not there any more on 6 October. It can therefore not be backed up. 

    But what neglect to mention in your example is the backup on 30 September, which would be a full and would have the file (if it existed) as is on the 30 September. This might or might not be helpful to the user.

    • Junz's avatar
      Junz
      Level 3
      6 years ago

      Hi Riaan,

      Thanks for your reply. But what if he only created the file on 1 Oct not before 30 Sep, then on 3 Oct the file was disappeared "myteriously". Plus the daily backup image on 1 Oct was expired also. Is it still possible to recover it with full backup?

      Thank you.

      • RiaanBadenhorst's avatar
        RiaanBadenhorst
        Level 6
        6 years ago

        No, since it was not backed up on the 6th by the 3 month retention policy and the 2 week retention has expired.