Backing Up Large 'Backup File' drive RRS feed

  • Question

  • We have a number of large backup files stored on disk produced by a third party backup tool. We need to back these large files up periodically to tape however this process tends to be a little on the slow side.

    For instance, if I have a volume with the following files on...





    ... and I kick off a tape based backup of the volume these files sit on, then tape backup overruns.

    What happens if LargeFile.2 is modified on disk and is actively used during the tape backup? Am I correct in thinking that a snapshot of the whole volume is taken via VSS when the tape backup starts, then the tape backup uses this VSS snapshot as the data source for the tape backup? Therefore if modifications are made to LargeFile.2 whilst the backup to tape is running the data going to tape is unaffected and thus not in a corrupt state?

    • Edited by FNK0ID Monday, April 15, 2013 3:10 PM
    Monday, April 15, 2013 3:08 PM

All replies

  • My original question wasn't overly clear sorry.

    If I'm backing up the volume described in the previous post then a new largefile.5 is created and written to whilst the tape backup is running, will consistency checks fail on the tape backup because largefile.5 wasn't there when the backup started but it is by the time consistency checks start to run?

    Saturday, April 20, 2013 3:21 PM
  • Hi,

    I'm assuming that you are doing Disk to Tape (d2t) backup, and you have configured DPM to verify your tape backups.

    If the above assumption is correct, then DPM will create a snapshot of the source volume on the protected server before it starts the backup, mount that snapshot, and copies the data from the snapshot to the tape.  Any file activity (file IO / new files added or files deleted)  on the volume will not effect the current tape backup job.   DPM tape verify after backup job only verifies that the tape is readable (no IO errors) and does not physically compare the source data with the data on tape, so changed data during backup will not effect the verify. 

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Friday, April 26, 2013 11:53 PM