SSD’s base memory unit is a cell, which holds 1 bit in SLC and 2 bits in MLC. Cells are organized in pages (usually 4k) and pages are organized in blocks (512K). Data can be read and written in pages, but is always deleted in blocks. This will become really important in a moment.
Vendors don’t share write amplification numbers – but you can use APIs they sometimes provide to check how much data is written when you write 1M
This means that write performance is throttled by disk which is why Exadata can do 60 reads for each write.