>(set compressalways no and that will fix the problem)

Dwight - A good explanation of what's going on.

Unfortunately, the customer is beset by conflicts in dealing with this problem.
Using COMPRESSAlways=No itself causes problems in Backup, as whole transactions
have to be reprocessed if one file grows during compression such that it has to
be re-sent uncompressed - and hence the Aggregate containing it.  This
inflates backup times, as some customers have been complaining about.

Rather than fix the *SM functionality problem, Tivoli instead greatly expanded
the error message description to describe circumventions that the customer may
perform to get around this.  Some APARs on message ANR0534W reveal that Tivoli
has taken steps in limited areas to boost their estimates of the space needed
in the storage pool so that some client transactions don't fail.  They need to
go on and fix the underlying algorithms to eliminate the problem rather than
leaving it to the customer deal with it.

     Richard Sims, BU