I am using SharePoint 2013.
- Is there any way to create more than one content database for one site collection?
- Is there a way to increase the size limit of a content database using RBS or any suggested tool?
Whilst a content database can contain more than one site collection. A site collection however, can contain only one content database. RBS can be used to prevent database growth as it stores data in physical location. See more about RBS here: https://technet.microsoft.com/en-us/library/ee748649.aspx?f=255&MSPPError=-2147217396
If your site collection grow beyond the 200GB(i am guessing you hreach 200GB not 4Tb) limit, i would highly recommend that perform the cleanup operation on the site collection and delete the unwanted stuff. Or split the site into multiple site collections so that you can easily manage these. Tip: maybe you push all archived data to new site collection to free some space.