I've been playing around with the raw data inside an 8GB Memory Stick, reading and writing directly into specific sectors, but for some reason changes don't remain consistent.
I've used Active @ Disk Editor to write a string at a specific sector and it seems consistent when I read it through Active (it survives unmounting, rebooting...), but if I try to read it through terminal using dd and hexdump the outcome is different.
Some time ago I was researching ways to fully and effectively erase a disk and I read somewhere that solid state drives such as flash drives or SSDs have more memory than it's stated so its internals keep replacing parts of the memory in order to increase lifespan or something like that.
I don't know if it is because of that or if it's even correct. Could you tell me if I'm wrong or where to find good documentation about the subject?
Okay I just figured it out.
Apparently when you open a disk inside a Hex editor there's two ways you can go, you can open it as a physical disk (the whole disk) or as a logical disk, aka a volume or a partition.
Active @ Disk Editor was opening it as a physical disk, while using dd and hexdump was dumping it as a logical disk. In other words it was dumping the content of the only partition inside the physical disk. This means there was an offset between the real physical sectors where I was writing data using Active and the ones that I was reading (quite a big offset, 2048 sectors of 512 bytes each).
So changes were being made, I was just looking at the wrong positions. Hope this saves someone a few minutes.