That is a 1st gen Seagate SMR drive, never had one but remember reading write performance isn't great, 2nd gen Seagate drives like the ST8000AS0002 usually perform well enough with Unraid, the ones I have are about as fast as normal CMR drives for most cases, Toshiba and WD SMR drives (and possibly other Seagate models) don't perform as well, I have an array with Toshiba drives that frequently slows down to 5MB/s for writes.