Following the demise of one of the pair of ST4000DM004 disks the ST8000DM004 been ordered to replace it. The old disk did not last long suggesting the low cost drive managed shingled disks are not as durable as older models. The write speeds are slow but read speeds are slightly more stable.
The 8TB capacity is adequate for general purposes such as media or file history etc. The performance of the drive managed shingled hard disks is mediocre which is why SSD drives are now very common.
The Corsair Obsidian 750D with 9 drive bays makes it powerful for media editing and gaming as well. Eventually the average capacity of the machine will rise as older lower capacity disks are either obsoleted or are removed due to drive failure. With one 12 TB disk and three 8 TB disks there is now lots of room for games.
Western Digital has not been competing as much in the hard disk market following some problems drive managed shingled disks. While they have lower capacity disks they do not offer 8TB models with a full 4 plates. Western digital only has 6TB disks. Western digital has segmented their product line which makes it even more difficult to select a suitable model. In the high capacity Western Digital has used shingled media for an 18TB disk to avoid using heat assisted technologies.
iTunes media is the intended use of the new disk. The existing 8TB disk will be repurposed for additional games.
Checking in with NewEgg shows that after buying the disk there are none left. Apparently I bought the last one in stock. Chia is a new crypto venture that now has been using hard disks and SSD to take a grab at the gold rush mentality.