Buy recertified enterprise grade disks from https://serverpartdeals.com. Prices were around $160/16TB the last time I checked. Mix brands and models to reduce simultaneous failure. Use more than 1-disk redundancy. If you can't buy from SPD, either find an alternative or buy external drives and shuck them. Use ZFS to know if your data is correct. I've been dealing with funny AMD USB controllers recently and the amount of silent data corruption I'd have gotten if not for ZFS is ridiculous.

Check out blackblaze drive stats, https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data

Any hard drive can fail at any time with or without warning. Worrying too much about individual drive families' reliability isn't worth it if you're dealing with few drives. Worry instead about backups and recovery plans in case it does happen.

Bigger drives have significantly lower power usage per TB, and cost per TB is lowest around 12-16TB. Bigger drives also lets you fit more storage in a given box. Drives 12TB and up are all currently helium filled which run significantly cooler.

Two preferred options in the data hoarder communities are shucking (external drives are cheaper than internal, so remove the case) and buying refurb or grey market drives from vendors like Server Supply or Water Panther. In both cases, the savings are usually big enough that you can simply buy an extra drive to make up for any loss of warranty.

Under US$15/TB is typically a 'good' price.

For media serving and deep storage, HDDs are still fine and cheap. For general file storage, consider SSDs to improve IOPS.

I'd like to second the 'manufacturer doesn't matter, all drives are going to fail' line, but specific models from manufacturers will have a much higher failure rate than others.

Backblaze, for example, publishes quarterly(ish?) stats showing the drives with the highest failure rates in terms of percentages, so you can kind of get a good view on if there's a specific drive model you should maybe avoid.

Or just buy an actual enterprise drive, avoid SMR, and have backups is also a sane approach.

I’d start with Backblaze’s 2023 drive report

https://www.backblaze.com/blog/backblaze-drive-stats-for-q1-2024/

There are two types, CMR and SMR. You can read online about the differences. CMR is better because SMR tries to be all fancy in order to increase capacity, but at the cost of speed and data integrity.

It won't be front and center in the specs of a particular drive, but you usually find the info somewhere.

I wouldn't worry about higher capacity failing sooner. If you have 10x4TB vs 2x20TB, that's 5x as many drives to go bad. So a 20TB drive would need a 5x worse fail rate to be considered worse. A pro of larger (fewer) drives is lower power consumption. 5-10 watts per drive doesn't sound like much, but it adds up.

I've heard very good things about resold HGST Helium enterprise drives and can be found fairly cheap for what they are on eBay.

I'm looking for something from 4TB upwards. I think I remember that drives with very high capacity are more likely to fail sooner - is that correct?

4TB isn't even close to "very high capacity" these days. There's like 32TB HDDs out there, just avoid the shingled archival drives. I believe the belief about higher capacity drives is a question of maturity of the technology rather than the capacity. 4TB drives made today are much better than the very first 4TB drives we made a long time ago when they were pushing the limits of technology.

Backblaze has pretty good drive reviews as well, with real world failure rate data and all.

One thing no one will tell you HOW LOUD some HDDs could get under load. You may not want any of those disks around if you’re keeping your server around your living spaces.

Just check dB values in the spec sheets.

I use Seagate Ironwolf 4TB drives in mine. Bought them all used, $50-60 each. Check on eBay and Facebook marketplace

My last I have bought are the Toshiba N300 15tb helium drives.
Didnt write much to it but they were cheap and seemed quiet enough to have around in my room (where I also sleep)

One important thing, ensure the drive is CMR, the reason is that you likely want a RAID, and non-CMR disks take so long to read the entire disk that the chances of a second failure while recovering from a disk failure is significant.

That being said, how are you keeping track of the disks state? I built my RAID recently, and your post made me realize that I have nothing to notify me if one of the disks shows early signs of problems.

At home I use two Toshiba MG09ACA18TE's and they work like a charm. I've bought them at around US$20/TB and it was the best price/TB offer at that time.

At work we use Exos X18's and Exos X20's without any problem at all.

I’m looking for something from 4TB upwards.

If you say "harddrive" ... do you mean actual harddrives or are you using it synonymous with "storage"? If you really talk about actual harddrives, it's hard to even find datacenter/server harddrives below 4 TB. Usually server HDDs start with 8 or 12 TB. You can even find HDDs with 20 TB - Seagate Exos series for example, starting at around 360 Euros (ca. 400 USD).

If you're in for a general storage, preferably SSD, that's another issue. There is the Samsung 870 QVO (8 TB) SSD that is often advertised as "datacenter SSD" (so I assume it would run well in a server that is active 24/7), but it is currently available with a maximum of 8 TB. The 870 QVO is at ca. 70 Euros per terabyte (ca. 77 USD) which, in my experience, is the current price range for SSDs. So it has a high price seen from the outside but it's actually fine. It's also a one-time investment.

For selfhosting I'd go with an SSD-only setup.

do any have particularly good or bad reputation?

From personal experience I'd say, stick with the "larger" brands like Samsung or Seagate.

I have an external usb hdd , wd passport 3TB from 10 years ago (healthy) connected to a Chinese N100 mini pc. I have proxmox on it, 5 lxc containers, 30 docker containers running apps, plex, calibre web.

I would say Seagate Exos or Western Digital Ultrastar.