A little dump question about Full and Transaction Log Backups

  • I have this scenario.

    If I'm doing a Full Backup and by mistake the schedule for a Transaction Log Backup start the job for this task after the full is initiated, did this generate some kind of lock that affects the database usage?

    My two cents it's not, because the Full action blocks the Tlog backup and until the full is finished the log is performed, therefore, any operation will be written to the Tlog

    I have a big discussion about this in the office so I need to know if my theory is right or wrong

    Any help will be appreciated

    Regards

  • Yes, it will wait until the FULL is finished before starting the transaction log. From Books Online:

         The transaction log cannot be backed up during a Full database backup or a differential database backup. However, the transaction log can be backed up while a file backup is running.

    There are a few other things you can't do during a backup (from BOL again):

    SQL Server uses an online backup process to allow a database backup while the database is still in use. The following list includes operations that cannot run during a database or transaction log backup:

    • File management operations such as the ALTER DATABASE statement with either the ADD FILE or REMOVE FILE options; INSERT, UPDATE, or DELETE statements are allowed during a backup operation.
    • Shrink database or shrink file. This includes autoshrink operations.

    If a backup is started when one of these operations is in progress, the backup ends. If a backup is running and one of these operations is attempted, the operation fails.

  • Thanks a lot man, sometimes the people make you wonder if you are right or not with some things, because there are just too negative

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