Advice Needed

We have a system supplied by a software house which uses an Informix database. We've noticed that the overnight dump which secures all our client records runs in approx 14mins and we're a bit suspicious of this - the client data is approx 500mb and the dump is informix level 0 to digital tape(HP hardware). The supplier thinks this is probably OK but tells us the only way to check is to restore from the dump!!. We instinctively feel something is not right but we don't have any Informix skills in-house to allow us to check it. I would welcome any advice on: (a) are we right to be suspicious are are we being paranoid? (b) is there any way of checking an informix dump other than restoring it - which presumably will destroy whats already there. (c) at the risk of opening the floodgates - can anyone recommend a supplier of technical - dba - training in the UK. Thanks, John Hepburn