Thanks for the heads up about clients only allowed to belong to one cell manager. I'll have to research how easy it is to move a client from one cell manager to another as that would be a huge deal if we couldn't easily restore. On those clients that have the most frequent restore requests they are rarely over a month old. But we do have some archived tapes that we keep "forever" just in case. I think I can import those into the new data protector version though. I could import them into DP8 (onto the D2D), then put them back on tape via the DP8 instance giving me a tape restorable copy for DP8. I don't want to keep archival data on the D2D. Waste of space.
We won't have the budget to purchase the D2D library until next quarter which is why I was thinking of MoM as a stop gap. Realistically I won't have the D2D solution implemented for 6 months, so do I limp along as is or go through the hassle of setting up MoM. I'll look at the documentation you recommended for DP 5.5 and try to decide if it's worth the hassle.
I read somewhere that you could split the catalogs into two separate ones and have some clients log to one and some to another. Unfortunately I haven't found it documented anywhere HOW to do this, only that this is an option.
I'm our SAN admin too. One thing that drives me nuts is when I get asked for more disk space and if I question the request I hear "But I can go down to Fry's and buy a 2 TB drive for $69!". Ok, go ahead. No one ever thinks about this stuff needing to be backed up!