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Does differential backup creates LSN ?

  • September 5, 2013 at 12:48 am

    #282142

    Hi All,

    I have a query regarding differential backup. I have taken full backup F1 and Differential backup D1 and then Transaction backup T1 again I am taking D2 and T2 and D3 and T3 in sequence. What I see, I can restore F1 and all T1,T2 and T3 without restoring any differential backup(D1,D2,D3). And my db is restored. Please let me know if Differential backups have generated LSN then how I was able to restore F1 and all Ts without restoring any Ds.

    Thanks in advance.

  • September 5, 2013 at 1:12 am

    #1647585

    All backups have LSN, there is just a bit difference in the relation between these LSN's. A differential backup is depending on the previous FULL backup. You can find the LSN of this FULL backup in the backupset of the Differential backup.

    The LOG backups are independent of the differential backups. The LOG backups form a sequence starting from the first FULL backup.

    So to restore a sequence untill you last LOG backup (T3) you have the following options:

    1. Restore F1, D3, T3

    2. Restore F1, D2, T2, T3

    3. Restore F1, D1, T1, T2, T3

    4. Restore F1, T1, T2, T3

    The differential backups can shorten the restore process because they 'include' all changes untill that moment and you don't need to restore all previous LOG backups.

    ** Don't mistake the ‘stupidity of the crowd’ for the ‘wisdom of the group’! **

  • September 5, 2013 at 1:47 am

    #1647600

    Thank you very much HanShi.

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