Do you have a source for that claim? Everything I've read suggests that data retention is mostly about the write temperature vs storage temperature, and that enterprise drives have about equivalent retention to consumer drives.
By retention I'm assuming you're referring to the amount of time it takes for data loss to occur on SSDs in cold unpowered storage.
Correct me if I'm mistaken but it looks to me like your graphs are talking about the number of P/E cycles accumulated, rather than the number of P/E cycles that a drive is rated for?
What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse.
But I don't see how that can be taken to imply that enterprise drives have worse data retention than consumer drives. Nothing that I've seen suggests this.
> What this seems to suggest is that as a drive gets more "worn out", its data retention gets worse.
This is what informal tests (i.e. via scrubbing/resilvering the drive after leaving it powered off for a long time) have found. Retention/data remanence is remarkably good for a drive that has been written over just once, and quite bad (i.e. you start seeing bit errors) for one that's almost worn out. This is actually very good news for the EEPROM-like use case where rewrites are quite rare.
(Note that "almost worn out" in this case can mean going far beyond the formal total-data-written rating of the drive. We're talking the range where the hardware itself is about to croak.)
I'm not sure I fully understand what that page is saying.
It is my understanding that JEDEC standard tests the data retention of the "worst case" scenario where a drive is fully worn out, i.e the drive has reached its maximum rated P/E cycles.
If I'm understanding correctly, that page you linked is saying that enterprise drives have firmware that essentially allows more P/E cycles, which then means that at the end of those cycles, the drive will be more "worn out" and thus will have a worse data retention.
But in a real world usage scenario where we subject a consumer SSD and an enterprise SSD to the same number of P/E cycles, would they have different data retention? I thought the JEDEC data was only for end-of-life scenarios.
fully worn out, i.e the drive has reached its maximum rated P/E cycles.
That differs between enterprise and consumer - and the reason why the former is rated higher is because they've reduced the retention spec (to almost 1/4th).
But in a real world usage scenario where we subject a consumer SSD and an enterprise SSD to the same number of P/E cycles, would they have different data retention?
No, and that's the whole point of this: the same flash, with different definitions of "worn out", is quite misleading as they're just looking at different points on the same curve. It's all obfuscated marketing.
Incidentally, this is also why those widely-publicised tests that claim SSD endurance is not a problem by continuously writing until absolute failure and seeing many times the rated endurance (e.g. https://linustechtips.com/topic/327024-the-ssd-endurance-exp... ) are extremely misleading (albeit enlightening on how "enterprise" ratings are being calculated): they are showing how many cycles the flash will take before it's too leaky to store data long enough for the next verification pass, which may be less than an hour away. At that point it's almost behaving more like DRAM than nonvolatile memory.
Oh wow, yeah I see your point, that is indeed extremely misleading.
I had always thought that enterprise SSDs used higher quality flash than consumer SSDs because of the higher endurance guarantees - that was why I bought them. Now I feel like a big reason to buy enterprise SSD has been removed.
I am flabbergasted, to be honest. And I feel a bit cheated that I am paying much more for the same quality flash.
So would it be fair to say that the only reason to pay for the enterprise SSD premium is the power loss protection and more reliable firmware?
Definitely don't think of enterprise vs consumer SSDs as good vs bad; they're optimizing for different use cases.
Enterprise SSDs get you power loss protection and firmware QA aimed at server workloads and operating systems, and performance tuning prioritizing consistent sustained performance, and larger form factors with enabling higher capacity and higher power.
Consumer SSDs get you higher peak performance (eg. SLC caching) and orders of magnitude better idle power savings and QA against Windows and its NVMe driver, in form factors suitable for laptops and not requiring direct airflow over the SSD.
A very long time ago when the SSD market was still quite immature, there was a time period where "consumer" SSDs were little more than cut-down enterprise SSDs with inferior NAND and fewer features. But that changed well before NVMe showed up.
> But in a real world usage scenario where we subject a consumer SSD and an enterprise SSD to the same number of P/E cycles, would they have different data retention?
Probably not, assuming they're using the same underlying media and same strength of ECC and that the amount of host data written was appropriately adjusted to account for the different capacities and overprovisioning ratios to ensure the actual P/E cycles seen by the NAND were the same.
As you write more data, the consumer drive would be out of warranty first, while the enterprise drive would still be under warranty but not spec'd to retain data for as long as the worn-out consumer drive. So for either drive, the manufacturer isn't guaranteeing 1 year retention past the rated endurance of the consumer drive.
