A:Answer Alright, two answer, one has more details taken into account than the other.
Simple Answer: The hard drive should operate at up to 190MB/s under ideal situations (I'd guess closer to 160MB/s on most computers#. This is based on the spec sheet for Seagate's 8TB Archive HDD #ST8000AS0002# which is the actual HDD inside this unit.
Technical Answer: It depends partly on your computer, people using older USB 3.0 ports or running Windows 7 #which don't support UASP, or USB Attached SCSI Protocol# will lose about 15-25MB/s off the top speed of the drive. Additionally, the 8TB Archive drive does not respond well to continuous writes since it uses a technique called SMR and may slow down significantly after a certain amount of sustained writing. #This will likely only be an issue during initial backups, video recording, or similar workloads, but I haven't actually used one myself to know where the limits are exactly)