quite un ugly hack for CLASSIC server would be making an UDF, that
would call gstat and pass its output into SQL space. For SuperServer
that would be risky approach though.

----

iberror.h in 2.0.x introduced isc_wrong_backup_state error code,
though I don't know what can trigger it

ibase.h introduces number of nbackup/nbk related options in 2.1 but
not in 2.0...