Drive size limit for Hyper-V & GRT backups

Hi,

I am running BE 15 on a Hyper-V server 2012 R2 network.

I have started to get GRT errors on the catalog of a fileserver drive. The drive size is 2.4Tb and used capacity has recenty gone over 2Tb. Is there a 2Tb size limit for such backups to allow GRT? I have seen some references in various forums but noting very clear. If so, does the 2Tb relate to used capacity of the drive or could I split the sdrive over multiple backups?

Thanks,

Julian