While consumer boxes like our most recent box use a single NVMe PCIe SSD. Some higher priced motherboards have dual slots. Some laptops may use a slot for LTE or 5G internet.
Servers at Azure etc are buying more and more machines loaded with SSD arrays. While more expensive, prices for SSD arrays have fallen over time while capacity has grown.
The money spent on the SSD boxes is now starting to exceed the money spent on hard disks. Servers are often stacked as a class and resources are handled through iSCSI or over the LAN etc.
I like the idea of a hybrid approach where a rack has a 4U hard disk server and maybe a 4U SSD array. Then a few 7U blade chassis make up the rest of the rack. This offers the rack’s best network speeds.
Azure has SSD storage for database servers which are the best bet. SSD storage for busy web sites is also readily available. Lower costs are making SSD choices much more affordable.
Azure has positioned hard disks into a few tiers. Hot, cool and cold are generally allocated for those who may be using content collections of relatively limited bandwidth requirements.
PostImage is one example where images for forums etc may get a few page views for a period of time before the discussion changes to a new topic. The need for high performance is not needed.
Azure pricing is pretty low cost for CDN type operations. Some CDN businesses use their own servers which sometimes makes sense. A 19″ rack with a bunch of hard disk boxes can hold a staggering number of images.
Many years ago when Usenet was more widely used, many hosts used RIAD boxes with smaller capacity disks. Now a single hard disk can handle the whole data stream for several months before it is filled. So a modern storage server can handle years and years of posts.