Tivoli Storage Manager is usually configured differently -- there are Storage Sets defined, which are connected to TSM Nodes, which have policies defined to retain documents for a fixed period of time (usually 3, 7, or 10 years). This config leads to the problem that Steve is experiencing -- a change in retention means an export / import cycle, or modifying the retention in TSM, leading to other issues. I've been recommending that CMOD is configured with One App Group associated with one Storage Set, which is connected to one TSM node for several years now.
-JD.