Do you just source these from eBay? Any guidelines for what's a good used enterprise SSD? I had considered this route after I built my ZFS array based on consumer SSDs. The endurance numbers on the enterprise drives are just so much higher.
>Any guidelines for what's a good used enterprise SSD?
Look at the sellers other items. You want them to be data-center stuff.
Look at how many they have to sell - someone clearing out a server won't have 1 drive, they'll have half a dozen plus.
Look for smart data in the post / guaranteed minimum health.
I mostly bought S3500/3600/3700 series intel SSDs. The endurance numbers vary so you'll need to look up what you find
>The endurance numbers on the enterprise drives are just so much higher.
That plus I'm more confident they'll actually hit them
Micron, Samsung and Intel (enterprise, branded DCxxxx) / SK Hynix / Solidigm (Intel sold it's SSD business to SK which they merged into Solidigm) are the go to's for brands. HGST can also be good.
The best guideline is buying from reputable sellers with a decent volume of business (eg, >1000 sales with high ratings on ebay) that focus on enterprise hardware and have a decent return/DOA policy.
You should expect these drives to be partially worn (regardless of the SMART data, that often gets wiped) if for no other reason than the secure erasure process mandated by a lot of org's data security policies resulting in multiple intensive disk writes, but also due to actually having been used. Drives that have recently been released (within 12 months, eg Micron 7600) are suspect as that implies there was a bad batch or that they were misused - especially if they aren't write focused drives. Not uncommon for a medium to smaller-end large business pinching pennies and buying the wrong drives and then wrecking them and their vendor/VAR rejecting warranty claims. That said, that's not always the case, it's entirely possible to get perfectly good recently made drives from reputable 2nd hand market sellers, just don't expect a massive discount in that case.
Otherwise best advice I can give you, is redundancy is your friend. If you can't afford buy at least 2 drives for an array, you should probably stick to buying new. I've had a few lemons over the years, but since availability on the second hand market for any given model can be variable and you tend to want to build arrays from like-devices, you should purchase them with the expectation that at least 1 per batch will be bad just to be safe. Worst case scenario you end up with an extra drive/hotspare.
I'd rather see 3Pb of 5Pb writes used than an obviously pretend 2Gib written.
If you're US domestic market, then yeah, you can usually avoid Chinese vendors. If you're EU or elsewhere, China can often be the main/only source of affordable drives vs domestic market. Really depends (I don't shop for international buds/clients, but I constantly hear about how the homelabbers across the pond have significantly higher prices/lower availability for surplus enterprise gear in general)
Stick to the rules on reliable vendors with a return policy, buy in bulk with the expectation that some will be bad (not a given, but good to be prepared), and the only issue from buying from china is delayed shipping times.