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Wow. And the 840 is still going error-free. That's pretty impressive.


The longevity of the 840 pro vs the silent failure of the 840 makes a really good case for the pro.

>The Samsung 840 Series started reporting reallocated sectors after just 100TB, likely because its TLC NAND is more sensitive to voltage-window shrinkage than the MLC flash in the other SSDs. The 840 Series went on to log thousands of reallocated sectors before veering into a ditch on the last stretch before the petabyte threshold. There was no warning before it died, and the SMART attributes said ample spare flash lay in reserve. The SMART stats also showed two batches of uncorrectable errors, one of which hit after only 300TB of writes. Even though the 840 Series technically made it past 900TB, its reliability was compromised long before that.


Note that they seem to be running a sample size of one. To add an anecdote, my own 840 Pro, after relatively little use, died completely and without warning one random day.


Yeah, the random controller failures are really what kills SSDs. This test has been all about proving that wear leveling works and write endurance isn't the thing to be worrying about.


Where did you see that the 840 is still going error-free? It says that the 840 maxed out it's reallocated sectors at around 900TB and veered into a ditch right before the petabyte threshold.

It'd be interesting to run these same tests on enterprise grade drives as well.

Edit: You meant that the 840 Pro is still going, I see.


840 has TLC, 840 Pro MLC

TLC cells should sustain 1-1.5K Program-Erase cycles

MLC 3-5K P/E cycles

eMLC 10-30K P/E cycles

SLC >100K

256GB eMLC SSD with 10K PE should be able to sustain 2.56PBW, which is pretty much what the 840 Pro 256GB with MLC was able to sustain in the test.

Also enterprise ssds usually come with huge overprovisioning, a raw 1TB drive usually comes with 800G usable space.

I had few 720G fusion iodrives with 1.1PBW and 0 reallocated sectors, and these were rated 10PBW.


I think so, yeah. That's one of the reasons I paid a bit extra to put an 840 Pro in my main development box.


Yeah: the 840 died but the 840 Pro is still going.


Yeah, I meant the 840 Pro. Sorry.




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