Modern hard drives have warrantee limits on how many bits you can read/write during their service lifetime, since they lower the head from about 10nm to 1-2nm during reads and writes, and head lifetime is correlated with the number of hours it spends at that 1-2nm height.
With workload specifications in the range of 500TB/year (IIRC - I took a quick look and couldn't find any recent specs) that works out to less than QLC levels of endurance. It's not the same, though - if you read/write every byte of a hard drive 300(?) times the failure rate rises and the vendor gets nervous; if you overwrite QLC 3000 times it's on its last legs, and 1 or 2K more writes will almost certainly kill it.
SSDs have quite predictable durability, mostly because the unit that fails is less than 1GB, so the law of large numbers kicks in.
Note also that "durability" is a soft target - the normal failure mode is that blocks retain their data for shorter and shorter times before hitting the ECC error limit, so if your storage system moves data around every few months you can push the flash harder than in e.g. a laptop, where you don't want to risk losing all your data if it sits powered down on a shelf for half a year.
>SSDs have quite predictable durability, mostly because the unit that fails is less than 1GB, so the law of large numbers kicks in.
You're forgetting the controller, which has no qualms with dying 100% unexpectedly. I don't know why consumer SSDs have such poor quality controllers that they can randomly die, something that HDDs seemingly haven't struggled with in decades.
Without access to vendor tools (like a JTAG debugger and source for the controller) I'm not sure it's possible to tell whether the controller itself failed, or it just decided not to wake up because the flash was dead.
But yeah, it sucks.
Finally, I'd note that a lot of earlier SSD vendors came out of the USB device market, where they were used to making things that had the reliability requirements of your average Happy Meal toy. There are only 2.5 hard drive vendors or so at present, in large part because the ones who weren't fairly good at reliability are dead now.
Modern hard drives have warrantee limits on how many bits you can read/write during their service lifetime, since they lower the head from about 10nm to 1-2nm during reads and writes, and head lifetime is correlated with the number of hours it spends at that 1-2nm height.
With workload specifications in the range of 500TB/year (IIRC - I took a quick look and couldn't find any recent specs) that works out to less than QLC levels of endurance. It's not the same, though - if you read/write every byte of a hard drive 300(?) times the failure rate rises and the vendor gets nervous; if you overwrite QLC 3000 times it's on its last legs, and 1 or 2K more writes will almost certainly kill it.
SSDs have quite predictable durability, mostly because the unit that fails is less than 1GB, so the law of large numbers kicks in.
Note also that "durability" is a soft target - the normal failure mode is that blocks retain their data for shorter and shorter times before hitting the ECC error limit, so if your storage system moves data around every few months you can push the flash harder than in e.g. a laptop, where you don't want to risk losing all your data if it sits powered down on a shelf for half a year.