What happened at about the same time as the Thai floods is that areal density hit a brick wall. The timing is just a coincidence. The reason that 4TB remains th

What happened at about the same time as the Thai floods is that areal density hit a brick wall. The timing is just a coincidence. The reason that 4TB remains the cheapest capacity is that it turns out 4TB is the most you can store using a conventional four platter drive, which is the most efficient configuration to manufacture. AFAIK all 6TB drives have five platters which of course costs more to make. 8TB drives are either six platters in a helium filled case or five platters with shingled recording, the former being expensive and the latter having significant performance implications. Fortunately for Backblaze, their use case is relatively well suited for singled drives which is what makes 8TB drives economical for them.