Comment by mjw1007
4 years ago
« Data loss occured with a Korean and US brand, but it will turn into a whole "thing" if I name them so please forgive me. »
4 years ago
« Data loss occured with a Korean and US brand, but it will turn into a whole "thing" if I name them so please forgive me. »
> The models that never lost data: Samsung 970 EVO Pro 2TB and WD Red SN700 1TB.
The others would probably be SK Hynix and Micron/Crucial, right? Curious why he's reluctant to name and shame. A drive not conforming to requirements and losing data is a legitimate problem that should be a "thing"!
> Curious why he's reluctant to name and shame
My sense is he wants to shame review sites for not paying attention to this rather than shame manufacturers directly at this point.
Crucial seems plausible, but there's a surprising number of US brands for NVMe SSDs. I was able to find: Crucial, Corsair, Seagate, Plextor, Sandisk, Intel, Kingston, Mushkin, PNY, Patriot Memory, and VisionTek.
Micron/Crucial is the 3rd largest manufacturer of flash memory, most of the other brands in your list just make the PCB and whitelabel other flash chips and controllers (perhaps with some firmware customization, but they're usually not responsible for implementing features like FLUSH).
Toshiba/Kioxia is another big one, but they're based in Japan. The US brand could be Intel instead of Crucial, I suppose.
Looks like he works at Apple. Maybe what he's testing is work related or covered by some sort of NDA (e.g. doesn't want to risk harming supplier relations for the brands misbehaving)
I thought Crucial specifically designed some power loss protection as a differentiating selling point? Well at least that was the reason why I bought one back in M.2 days (gosh my PC is ancient...)
I think the most they ever promised for some of their consumer drives was that a write interrupted by a power failure would not cause corruption of data that was already at rest. Such a failure can be possible when storing multiple bits per memory cell but programming the cells in multiple passes, especially if later passes are writing data from an entirely different host write command.
Back in M.2 days? I know I'm getting old, but what did miss?
3 replies →
It changed [1] from capacitors and "power loss protection" to something else described as "power loss immunity" with the MX500. I don't think I've ever seen it explained very well.
> With the release of the MX500, Crucial has included a new replacement for the traditional power loss protection feature, power loss immunity. Instead of relying on a bank of capacitors for power loss protection, Crucial was able to work the new 3D TLC NAND and the code to allow for more efficient NAND programming so that the capacitors are no longer needed.
That's just a regurgitated press release IMO.
A lot of consumer drives also stopped reporting DRAT/RZAT [2] around the Crucial MX500, Samsung 850 timeframe. They swap internals as others in this thread have pointed out and the write endurance has dropped since reviewers stopped reporting on it. I have a Crucial MX500 in my system right now with 11% life remaining and only 37TBW even though it's advertised as having 180TBW of endurance.
Edit: I actually found [3] an explanation of "power loss immunity".
> The impact is still the same: you don't get the full protection that is standard for enterprise SSDs, but data that has already been written to the flash will not be corrupted if the drive loses power while writing a second pass of more data to the same cells.
I always thought write operations on SSDs were more or less to write a new page or block or whatever the terminology is and to flag the old one(s) for garbage collection. I don't understand how it would be possible to lose the old data by doing that. Did they just invent a term that sounds like power loss protection, but doesn't actually do anything special?
1. https://www.thessdreview.com/our-reviews/crucial-mx500-ssd-r...
2. https://forums.anandtech.com/threads/looking-for-new-ssd-tha...
3. https://www.anandtech.com/show/12165/the-crucial-mx500-1tb-s...
1 reply →