[aftbit]

Not the OP but I have a pair of Chenbro NR12000 1U rack mount servers, bought for about $120 each on eBay a few years ago. Each has 12 internal 3.5" mounting points and 14 SATA cables. In one server, I have 12 4TB used enterprise drives. In the other, I have 12 8TB drives. Both have 16 GB of RAM (should probably be more) and two 2.5" SATA SSDs. They are configured with two ZFS raidz1 vdevs, each made up of 6 disks. This gives me 10 usable disks and 2 used for parity, and the ability to survive at least one failure but maybe two (if I'm lucky).

I back up critical data from the 80TB NAS to the 40TB NAS, and the most critical data gets backed up nightly to a single hard drive in my friend's NAS box (offsite). Twice a year, I back up the full thing to external hard drives and take them out of state to a different friend's house.

Don't worry, be happy.

[sillysaurusx]

(Where are you finding friends with a NAS? Or at all, for that matter… guess I’ll look on eBay.)

Thank you for the details, particularly about zfs, which I know nothing about. The “if I’m lucky” part piqued my interest. HN was recently taken down by a double disk failure, which is exponentially more likely when you buy drives in bulk - the default case. So being able to survive two failures simultaneously is something I’d like to design for.

It’s cool you have two NASes (NASen?) let alone one. They’re the Pokémon of the tech world.

[aftbit]

Ah my tech friends have specialized into hardware a bit. At least two of us have server racks in our basement, and basically nobody I know (who at least knows the command line) does not have at least a few drives in an old Linux server somewhere.

If you are concerned about reliability above performance, I would suggest using a single raidz2 vdev instead. This would allow the cluster to definitely survive two disks worth of failure. I'll also echo the common mantra - RAID is not backups. If you really need the data, you need to store a second copy offline in a different place.

When I lived in California and did not have room for a server rack, I had a single home server with an 8-bay tower case. I used an LSI card with 2 SAS-to-4x-SATA ports to connect all 8 drives to the machine. I believe I had 6 TB drives in that NAS, though they are currently all out of my house (part of one of my offsite backups now). My topology there was 4x mirror vdevs, which gave me worst case endurance of 1 failure but best case of 4 failures, and at about 4x the IOPS performance, but with the cost of only 50% storage efficiency vs the 75% you would get with raidz2.

There is even raidz3 if you are very paranoid, which allows up to 3 disks to fail before you lose the vdev. I've never used it. As I understand, the parity calculations get considerably more complicated, although I don't know if that really matters.

[zuminator]

Interesting. It's been a while since I've used eBay, but man they've really upped their game if you can buy friends there now.

[fnordpiglet]

OP was pulling your leg a bit. Clearly the only friends folks like us have with NAS are the friends here on HN posting about their NAS.

[2f0ja]

What are you criteria for used enterprise drives? I'm wading into building a nas (well.. it's more of a 'project' nas as an above comment would say) and I'm getting a little lost in the sauce about drives.

[aftbit]

I just bought the cheapest "Grade A" drives I could find from eBay. This is not the reliable way to do it, but as I have a 3 layer backup solution anyway, I don't really mind the risk of a drive failure.

It depends on what your plans for the storage are. If you're going to fill it with bulk data that gets accessed sequentially (think media files), then performance will be fine with basically any topology or drive choice. If you are going to fill it with data for training ML models across multiple machines, you need to think about how you will make it not the bottleneck for your setup.

One more thing to consider - you can get new consumer OR used enterprise flash for somewhere around $45/TB in the 4 TB SATA size, or the 8 TB NVMe size. Those drives will likely fail read-only if they fail at all. They will usually use less power, take less space, and obviously will perform orders of magnitude better than spinning rust, at somewhere around 3x the cost.

I am hoping to build my next NAS entirely on flash.