If you look at your settings area, you have the option under Clients to backup up individual servers and Groups to setup a group of servers that will backup together – I’ve only ever used this for clusters, so someone else may have to guide you with group settings.
Once you’ve selected the client or group, or went to either File Backups or Image Backups in your global settings (meaning, you just went into the settings page shown above, and not an individual client) then you can set up the automated choices that you are referring to.
You can also leave it up to the client, under the permissions tab – if you so desire. I believe that any changes made on the client-side will propagate up to the server (referring to settings.)
Now you’re limited to the time-frame listed in those areas:
File Backups have an incremental every X hours and a full every X days.
Image Backups have an incremental every X days and a full every X days.
But you can set each retention up to how many copies you want, and how many you want to keep at a minimum.
There is also the setting Global Soft Filesystem Quota under the general section of your global settings; you can hard-limit it or set a percentage there.
As an example, if you set the quota to be 50% and you want to keep a certain amount of backups of each machine then the program will remove a certain amount of space while keeping your retention policy intact so that it can keep backing up.
Of course if you don’t set the quota, it will still do that, but the drive will be completely full – depending on your settings, how much you back up, and current space capacity.
The entire 8.X area may be useful to you regarding this: https://www.urbackup.org/administration_manual.html#x1-410008