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