The problem is that staff time costs an order of magnitude more and most of these things can go wrong. For example, you don’t just want to buy random lots of whatever disks are cheapest because then you have to track recalls and firmware updates for everything.

If you have two tiers available, someone will use the less reliable one because that’s how they fit their budget but then because it’s “in production” they’ll expect the same level of service.

All of these are manageable but what you’re really hearing is that the technical issues are really the tip of the social iceberg most organizations have. One of the reasons people pick AWS isn’t just that it’s usually cheaper than the full cost of rolling your own but that lots of these things don’t affect you: you never fail to provision an EBS volume because the VPs of finance and IT are still arguing about procuring a new rack of disks, people can’t request endless customizations because the options are “take it or leave it”, etc.

When you start requiring redundancy, you start needing 2-6x the number of disks, minimum.

Still cheap, but not that cheap.

Single disks are cheap. Multi-disk storage systems are not. Multi-tiered storage systems are even more expensive. I don't see an inherent conflict there.

Depends on the org. Some orgs are well managed, others don't want to pay for stuff behind the scenes until it bites them in the ass. They don't know what they don't know.

> and cage-free hard drives nowadays.

SOmewhat recently I toyed with an idea of HDDs with an 'interposer' which would be just a dumb ATA2iSCSI interface, with Ethernet or WiFi connectivity.

That would allow you to place those drives literally anywhere and with a minimal footprint.

Sadly it would be too costly for the home usage (I assume about $30/unit at best) and for the enterprise usage... 1Gbit is too slow, 10Gbit is too hot and bulky and then you can't sell a $3 plastic case for $100 'vendor approved with light-path(r)(tm) diagnostic indication' for each drive.

Because the enterprise disks are rated for years of continuous service and have things like firmware which doesn’t lie about whether data has been committed durably for the sake of benchmarks on review sites.

None of this means that you should trust any particular disk enough not to need redundancy, backups, etc. Companies can and do make trade offs based on their needs and management competency and people have been shifting software for a generation to rely less on the hardware – back when Sun announced ZFS, one of the major appeals was that you could drop expensive hardware RAID controller dependencies in favor of cheap boxes of disks – but there isn’t a single global optimum point. A lot of enterprise purchases are driven by being able to satisfy your most demanding users with the same service as everyone else so you can avoid needing your admins to be trained and experienced with dozens of different storage systems. That last part especially extends to testing: for example, does your rack of consumer drives with software redundancy come back up cleanly after a kernel panic or power outage, especially a nasty one like a fluctuating brownout? Depending on your budget, needs, and technical bench depth you might reasonably conclude that the savings are worth the ops work, or that it’s safer to pay an enterprise storage vendor who’ll certify that they’ve done that testing and will have tech support on-sight within an hour, or that you’ll use AWS/Azure/GCP because they do even more of that tedious but important work. All of those can be right, but I’ve typically found that people in the first two categories think they’re doing better than they are and would be paying less for better service in the cloud.

Well, "enterprise storage" can actually be multiple, redundant copies of the data behind the scenes.

So, internally the storage team might quote say $1000/TB (simple numbers for an example) for a given storage quantity. And behind the scenes they'll likely have at least redundant storage arrays, plus backups and 24/7 monitoring for all of the data, etc.

Because if you're providing services to a large business, you're typically not managing servers with physical disks attached. You're using a SAN with fiber connections or NFS mounts. Most SANs require specific drives sold by the vendor with firmware they've tested, mounted to custom sleds etc. You can't just connect a WD Mybook drive.

Mom and Pop businesses using single servers can do all they want in regards to drives, I don't care. I would argue they shouldn't have servers, but if you do have servers, you should at minimum use RAID etc, not a drive plugged into your USB port.

It’s because all consumer disks are garbage. The way it works is that disks are tested. Disks without failures are sold as “Enterprise.” Those that have failures are labeled and sold as “consumer”, not thrown in the bin.