Confusion regarding which full-backup file to apply on secondary in Log shipping

  • Hi we have a log shipping configured at one of client side and is out of shrink for log time . Now client what has happened is that client has taken full backup of database of say on this 27 at 1.00 am and simultaneously transaction log backup job(of log shipping) was running , now on this 28 client took another full backup of same database , also transaction log backup is running and i have all backup file.

    My understanding is that due 28 th full backup all transaction backup file generated after 28, 1.00 am must have there LSN changed and so i ,must apply full backup file of 28th and then apply transaction log in order to brink secondary in shrink with primary but my friends say we can apply 27 backup file and then apply all transaction log backup file and as such no LSN change is broken.

    please tell me who is correct and

    Does file generated on 27 can be applied and then apply each transaction log files

  • Hi Anoop,

    The Full Database backup taken on 28th is sufficient enough and have all the transaction changes till the 28th. You can apply the 28th full backup and all the Transactional log backups(.trn) after that to bring the Secondary back In-Sync.

  • Both scenarios are valid as long as you have all of the log files. Full backups won't interfere with the LSN of the transaction log backups.

  • Hi plz tell me when is LSN chain breaks in case of log shipping.

    And as per my knowledge log transactions are dependent one full database backup files and for in that case LSN number is important.

  • The LSN chain for log shipping is only broken if a log is lost or corrupt. There are other scenarios, but all would envolve using differential backups and mutliple full backups.

  • anoop.mig29 (3/2/2013)


    And as per my knowledge log transactions are dependent one full database backup files and for in that case LSN number is important.

    Not true.

    Differential backups are dependent on one specific full backup, log files are not.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • GilaMonster (3/2/2013)


    anoop.mig29 (3/2/2013)


    And as per my knowledge log transactions are dependent one full database backup files and for in that case LSN number is important.

    Not true.

    Differential backups are dependent on one specific full backup, log files are not.

    Gail thanks for your reply . can u clarify one more doubt , that if i have full backup and log backup then do i require differential backup or not . if not then why options of differential backup are provided

  • Require, no. Full and log can restore to a point in time. There are advantages and disadvantages to differentials, there are many places where they are useful.

    Consider, for example, a scenario where a full backup takes 4 hours but the only time you have a 4 hour maintenance window is on a Sunday. What do you do for backups?

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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