Can you be more specific? There is no storage limit besides the size of the hard drive on your server, and of course you want to allow for a percentage of free-space.
Also, note the following 2 built-in server settings:
1. For defined sites within your server, you can allocate a specific amount of disk allowable. This is available to server admins via the settings interface.
2. The server admins can get alerts when unused disk space for the server drops below a certain level. This is configurable either through TSM (for 2018.x) or the old config panel.
3. There is a built-in admin report that will show you used disk space.