Just FYI, there does not appear to be a size limitation but there IS a limit to the number of objects that can be cataloged: 55 million.  This isn't advertised anywhere but I learned about this limit from engineering while trying to get a large backup completed. 
Does anyone know if there is a size limitation to the f_cache2.dat file? I have a very large backup and cant seem to get the cache file to grow past 12.8 GB (and a certain number of pages)
F_cache2.dat size limitations? (avamar client backup)