how are tapes allocated for full/incremental and what causes a tape to stop being used? RRS feed

  • Question

  • DPM2012 SP1 RU3, Windows Server 2012, Dell 24-slot two drive library

    Backing up two file servers with a total of about 1.5TB

    short-term tape: 3 week retention, daily backup, full and incremental. Full at 8:00PM Friday, incremental 8:00PM Mon-Th

    long-term tape: two month retention, monthly backup, last day of the month

    I created the protection group on 4/10, and a full backup ran that night, using one full tape.  No backup ran on 4/11, a Friday, as it appears there were no changed files and the full backup was already done.  Incremental backups all used the same, second tape 4/14 - 4/17, but used only 8GB on the tape.  The next full backup used a third tape on 4/18, again filling the tape.  The second week's incremental backups use a fourth tape.

    So, my question is, given my protection group parameters, is this the expected allocation of tapes?  Full on one tape, subsequent incrementals on a second until it's time for another full backup?  Is the incremental tape left mostly empty so that the full+incremental "pair" expire in tandem?

    Also, is there any way to force succeeding days' incremental backups to use different tapes? I'm concerned that damage to one tape could wipe out multiple incremental sets.

    Tuesday, April 22, 2014 4:05 PM


  • Hi,

    That is the way it worked in DPM2010.

    How DPM Uses Tape Libraries

    Since the introduction of the Optimize Tape Usage settings in DPM 2012, you can see if the write period and expiry tolerance settings effect how long tapes can be used for Full+incremental backups.  Historically the settings only effected long term tape backup goals, but have not played with them for short term tape backups.  Let me know what you find.

    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.

    Tuesday, April 22, 2014 7:43 PM