>Earlier on this morning we commenced a Space reclamation job but we being
>given multiple messages referring to different volume numbers, of the
>following type
>
>ANR1163W Offsite volume SPL500L1 still contains files
>                       which could not be moved.
>
>However after struggling for a little while we rebooted the server and thses
>messages appeared to stop.
>Can anyody shed any light as to why this has happened ?

Well, the Messages manual pretty much explains why this can happen.
In http://people.bu.edu/rbs/ADSM.QuickFacts I include some supplementary info.
You probably have some onsite volumes (used as representatives of the contents
of the offsite volume being reclaimed) which are unavailable or which contain
damaged files.  Check your Activity Log history for past tape problems, as well
as do Query Volume for volumes which are Unavailable or Destroyed.

  Richard Sims