Sorry for the tardy reply.
Thank you for your answer. I thought I had a Pegasus2, I was mistaken.
I ordered a replacement Hitachi HGST Deskstar HDS723020BLA642 but the company sent me a Toshiba 2 TB instead!
Now I am even more disappointed, your Pegasus1 compatibility list does not list anything larger than a 4 TB drive. :-(
These units cost quite a bit of money, I do not feel like I should have to buy an entire new unit (that I cannot afford) just to get larger capacity disks. (There was an amazing sale on Hitachi 10 TB drives a couple of days ago that I could not take advantage of.)
It seems unfair that I can only double my current capacity, I cannot buy these 10 TB drives to get 60 TB of raw capacity. I have no need for Thunderbolt 2 or 3 speeds in my home setup. The 4 TB drives in your Pegasus1 compatibility list are of limited availability these days. (How about certifying some more recent disks in your older products??)
Edited to add: (This is the wrong forum to ask in, but I will anyway.) The compatibility list for the Pegasus2 R6 lists the Toshiba MD04ACA600 6 TB drive. Is that same drive likely to work fine in the Pegasus1 R6? Even if it is too 'new' to be included in the Pegasus1 compatibility list?