My likely path away from spinning hard drives on my home desktop
One of my goals for my home desktop is to move entirely to solid state storage. Well, it's a goal for both my home and work machine, and I originally expected to get there first at home, but then work had spare money and suddenly my work machine has been all solid state for some time (which is great except for the bit where I'm not at work to enjoy it).
Moving to all solid state at work was relatively straightforward because all of my old storage on my work machine was relatively small; I had a mirrored pair of 250 GB SSDs, a mirrored pair of 1 TB HDs, and a third 500 GB HD for less important things, and none of them were all too full. This was easily all replaced with a pair of reasonable sized NVMe drives and a pair of 2 TB SSDs, which weren't that expensive even in late 2019. Unfortunately my home machine is better configured; I currently have a mirrored pair of 750 GB SSDs and a mirrored pair of '3 TB' HDs (one of them is a 4 TB HD, but since it's mirrored the extra TB is wasted). The HDs are used for a LVM volume that has only about 1.4 TiB allocated, so in theory I could get away with a pair of 2 TB SSDs as the replacement for these HDs. However, that would leave me relatively short of extra space for things like digital photography (those RAW files add up fast).
The obvious replacement and supplement for my current 750 GB SSDs is a pair of decent 1 TB NVMe drives, which seem to be not too expensive these days. Unfortunately there is not as good a replacement for my pair of 3 TB HDs. While 4 TB SSDs are available, they cost noticeably more per GB than 2 TB SSDs do (as I write this, one large Canadian online retailer lists WD Blue 2 TB SSDs for $304 and the 4 TB version for $709). One option would be to shrug and pay the premium for future proofing things; another would be to buy a pair of 2 TB SSDs and rely on a combination of the extra space on the NVMe drives, reusing my current 750 GB SSDs, and rationalizing space usage when I migrate from my old LVM setup to ZFS on the new SSDs.
A complication is that now is not necessarily the right time to buy new NVMe drives, especially relatively expensive ones. The NVMe world is just starting to move from PCIe 3.0 to PCIe 4.0, which offers various improvements once everything is working. My current home motherboard has no PCIe 4.0 support, of course, but based on past experience I'll be keeping any NVMe drives that I buy now for at least half a decade, which means that they'll likely wind up in a PCIe 4.0 capable system within their lifetime.
(On the one hand, PCIe 4.0 will probably not make a particularly visible performance difference on my home machine on typical or even somewhat atypical tasks, like compiling Firefox from source. On the other hand, I don't like leaving potential performance on the table.)
So despite all of what I've written, I'm probably going to do my usual thing and sit on my hands for a while. Perhaps various end of the year sale prices will get me to finally move forward.
(This is one of the entries that I write partly to try to motivate myself.)
PS: I have a mixed pair of 3TB and 4TB HDs for the usual reason, which is that I used to have a pair of 3 TB HDs and then one of them died and I needed to replace it. My LVM array has migrated up from smaller sizes of HDs over time this way.
(Waiting for a warranty replacement is never an option, because I want my redundancy back much sooner than a replacement would get to me.)