This probably applies to both 840 evo and 850 evo, but not the EVO 840 PRO and the 850 evo pro because the pro are not TLC
All over the internet, people are saying that solid state drives don’t need to be aligned because they will scramble the used flash cells anyway for wear leveling.
This is absolutely NOT TRUE, although wear leveling does work that way (in a simplified way), the mapping algorithm that levels the writes maps blocks to other blocks.
So here is how it works, let us assume there was no wear leveling, when the partition is not properly aligned to a starting offset which is a multiple of the eras block size, writes and erase operations that should require the erasing of one block could end up erasing and writing to two blocks, now the block is a hardware restriction, so when the wear leveling algorithm selects a new location, the problem of sing two cells instead of one is still valid.
Don’t take my word for it, mess up the alignment of one of your partitions, then examine reads and writes of 512 or 4K, both will be much slower.
Now, what you need to do is to align the file system to block size
Because this disk has a 1.5M erase block 1536 KiB and to be sure we want it to also align with 2048 KiB (Just in case the erase block is not the whole story), you can set the sector alignment value to 12288 (6144 KiB), which is a multiple of 1536 KiB and 2048 KiB.
So, in LINUX, even though it is usually correctly aligned by the partitioning software (And in windows it is already done for you and if not it can be done by samsung’s magician software), you can check the current alignment with.
fdisk -l /dev/sdb
For your own math, the EBS (Erase block size) on those drives is 1.5MBs
So basically, 12288 is 3*4k, the three comes from the fact that it is a three level cell (TLC)