Snapshots should be allow to easily go back in time.
As such, the following is offered by Solaris/OpenIndiana Time Slider:
|Name||Snapshot every||How many we kept?|
|frequent||15 mins||4 (=one hour)|
|hourly||hour||24 (=one day)|
|daily||day||31 (=one month)|
|weekly||week||7 (=two months)|
|monthly||month||12 (=a year)|
It would be a nice idea to implement this on Ysul.