7 Replies Latest reply: Jun 17, 2014 8:42 PM by Hemant K Chitale RSS

    compressed backup size differ between tape & disk

    Mike Kutz

      This is out of pure curiosity.


      DB EE on OEL 5.6 (64bit) + Adv. Compression

      TSM for MML


      Both disk and sbt_tape are configured for compressed backupsets

      compression algorithm is configured for 'HIGH'


      If I backup to disk, it takes 1.5hrs and produces a 10GB backup piece.

      If I backup to tape, it takes 5hrs and produces a 27GB backup piece.

      Watching "top", it seems like 1 core runs @ 100% with most of that (>90%) being "user" (ie not I/O bound or wait)

      (backing up the 10GB backup piece to tape takes <2 min over a 1GigE link)


      Has anybody else seen this type of size difference when they do a compressed backup to disk vs tape?

      Is this suppose to happen?

      Should I be concerned?


      Many thanks for any information,