As with any backups, simply taking them is only half the work - you should also make sure you can restore them. Unfortunately that's not as straight-forward as you would think with iCal Server.

Say one of your users has accidentally deleted a group calendar (R/W permissions mean the user can delete, but not create cals under a group delegate). This happened yesterday so you know you should have the calendar in last week's snapshot.

Here's what I found:

• Calendars are just folders stored under calendars/uids. Their mnemonic names are unfortunately hidden (probably in some DB). The only way to find the right folder is just to look at the events (the ICS files in the folder)
• Get the GUID from the web interface at principals/groups/groupname
• Because of this hidden DB layer it's not just enough to move the folder(s) back into place. The method that worked for me is to simply create the calendars by hand in iCal and then drag the contents of the folder onto that calendar.