I read the story but am somewhat baffled. It seems as though eXch hosted their servers in Germany and that seems a strange thing to do. Also, it was reported over eight terabytes of server data was seized. That is a lot of data and there were reports about CM having similar amounts confiscated at the time they were seized. having said that, no reports of arrests were made.
If I understand correctly, eXch had its own nodes for each coin they had listed on their platform. Full nodes on BTC, ETH, LTC, and Dash are certainly in TB-sized.
A full Ethereum archival node running the go-ethereum software that eXch was known to compile from source in the past, requires at least 12 TB.
https://geth.ethereum.org/docs/getting-started/hardware-requirementsHowever, if the full archival state is not stored, it could be under 2 terabytes.
The Bitcoin node requires about 600GB. Monero 100GB. Dash and Litecoin's blockchain size is negligible. However, Lightning network takes up a couple more hundreds of GB of space, depending on the client. If you also include the programs that eXch use like Thorchain for isntance, those uses several hundred gigabytes in total as well. We do not know exactly what software was eXch running on the server but it's highly likely that the nodes accounted for the bulk of the storage space.
Logs are not terabytes large. At most, hundreds of megabytes typically.