WD Offers 12TB HDD and 8TB SSDs Today, Promises QLC SSDs In The Future

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Jun 8, 2011
QLC would be the natural progression from TLC, and would lower the GB/$, fact.
However, just as the write endurance has been getting more focus lately when moving from SLC to MLC to TLC, data retention should be a parameter getting more focus moving onwards.
I can not recall reading about data retention in consumer HDD/SSD reviews ever! (My memory spans about 5 years or so, so leave a comment if you have).

Apparently these electrons and atoms that store our 1 and 0 are in the habit of taking a walk'about, and we don't want that!

I wouldn't mind getting a QLC flash based storage unit for archive purpose, if I knew that, the device, left untouched, still retained the data of all the cells after 1 year, or perhaps 5 years.

Ps. I do know that the first CD I bought still played after some 15 years (Depech mode: Enjoy the silence!). How it fares today I don't know; I'ts been converted into flac, sitting on a HDD... Ds.
I heard a recording somewhere (not Tom's) of people discussing SSD data retention a year or so ago. It shocked me that one of the techies in the discussion said that if you put one on a shelf it would start losing data after a few months but as long as it was powered up occasionally it would hold the data. So forget about using them for archiving.

The recording was probably on Ars Technica or ExtremeTech if you want to look for it. It was just a link at the bottom of one of the articles.

"Spinning rust" apparently has its uses.

I saw an article on one of the science sites recently that said scientists had determined that neutrinos do actually have a miniscule amount of mass. They are said to "rarely" interact with matter but "rarely" is not never. With billions of them passing through our bodies every second it makes me wonder about the stability of any kind of circuit, SSD or otherwise, as long as they keep shrinking the node size.

From a manufacturing point of view, however, that's a good thing - smaller node size would enable the devices to go kaput earlier if my theory about the neutrinos is correct. It would be a kind of built-to-fail (at some point) strategy.

I was kind of laughing at the 2.5 million hour MTBF's. Really? 285 years? Who would care?


Sep 23, 2013

The MTBF is a statistical tool and can't directly be used to arrive at the life span of a single drive. It *can* be used to estimate failure rates and risks in large pools of drives (like in data centers).

2.5 million is the mean. More drives will fail before it than after (since failure rates usually increase with time). Some small number will fail much earlier.

The problem with that is it would affect the enterprise segment just as well. It's not like they are going to create a separate design on a larger node.


Aug 31, 2011
Frankly when most TLC SSDs are expected to not last over 3-5 years of use without errors, QLC I think is stretching a bit. The moniker that normal consumers don't require them because their use is less is pointless brain washing. Us techies can still save ourselves through backups but the common consumer will have to face the loss head on and he will be extremely unreasonable when that happens.

I think longevity must have been the better metric rather than performance or cost because well we all know that no matter what happens QLC will always be slower than TLC, and similarly as we go up the ladder. Its the only segment of the industry that is getting inferior and inferior in quality.


Nov 21, 2008

Me neither. You'd have to treat it like a giant, slow RAM disk due to the data retention issues. I wouldn't trust it with any important data, not even temporarily. Turn off the computer for 2 weeks and the data might be gone.


Jun 16, 2007
QLC = "Hey my SSD stopped working, I only saved a blank word document to it"

CSR: "Are you crazy, saving that much data to the SSD? Even with a blank word document, you are talking nearly 1KB of data"
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