I'm talking about lifetime writes, not daily writes. If you look at the Samsung 850 PRO SSD specs page [1], the most important metric in SSD lifetimes is the n

I'm talking about lifetime writes, not daily writes. If you look at the Samsung 850 PRO SSD specs page [1], the most important metric in SSD lifetimes is the number of terabytes you can write, or TBW. Yes, they do list the reliability in hours, but if you hit the TBW first, then it's game over. Reliability for the 850 PRO: > MTBF : 2 million hours(125GB/256 GB/512 GB/1 TB), 1.5 Million Hours Reliability (2 TB) TBW: > 128 GB / 256 GB : 150 TBW, 512 GB / 1 TB / 2 TB : 300 TBW So the 2 TB model can (theoretically) be used for up to 1.5e6 hours, but if you write 300 TB, it will simply fail. This is all due to limitations of NAND flash at the device level, so it's essentially unavoidable. There are primarily two different techniques for NAND flash storage: SLC and MLC. In SLC, you store 1 bit per flash cell, whereas in MLC you store 2 bits per cell. Due to the nature of MLC, you need multiple reads/writes to read/store data for each cell. As a result, SLC SSDs are much more reliable, but this comes at a higher cost. Most consumer SSDs are MLC or even TLC (3 bits/cell). See [2] for more info. [1]: http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/ssd850pro/specifications.html http://www.samsung.com/global/business/semiconductor/minisit... [2]: https://itblog.sandisk.com/ssd-endurance-speeds-feeds-needs/ https://itblog.sandisk.com/ssd-endurance-speeds-feeds-needs/