Almost all SSDs internally track allocations in a 4kB granularity. That size is what leads to the convention of equipping the drive with 1GB of DRAM for every 1

Almost all SSDs internally track allocations in a 4kB granularity. That size is what leads to the convention of equipping the drive with 1GB of DRAM for every 1TB of NAND flash, when the drive is designed to hold the entire table of logical to physical address mappings in DRAM. It's now common for consumer SSDs to have less DRAM than the normal 1GB per 1TB ratio, but they run their FTL with the same 4kB granularity and just don't have the full lookup table in RAM. There are at least a handful of special-purpose enterprise drives that use a larger sector size in their FTL, such as the 32kB used by WD's SN340: https://www.anandtech.com/show/14723 https://www.anandtech.com/show/14723