I'd love for an option to have the snapshot retention be based on a GFS cycle. I would envision it being an option of retaining:
- The last X days
- The last X Weeks
- The last X Months
- The last X Quarters
"The end of the day" would be the daily snapshots
"The end of the week" would be the weekly snapshots
"The end of the month" would be the monthly snapshots
"The end of the quarter" would be quarterly.
Application logic would then treat the snapshots accordingly, rolling things into other things as needed to maintain it.