Hello Andreas, sorry to hear tat this sort of thing is still happening this century... Have you had a look at container pools and dedup? It would ease the storage-side pain quite a bit, with drawbacks in taking copies to tape. I have been testing the dedup + compression feature, an apart from handling of copies of the data, Data reduction has been impressive even with incrforever data with limited influence on performance. Test was with SP 7.1.6.0.
Kind regards, Markus