At least for SSDs the description I read was something like yes,you can write a single block if you only need to turn 0s into 1s, but no for the reverse, which requires erasing a whole group (forgot the precise term for that) of blocks.
In NOR flash erase actually sets all bits to 1. Afaik same thing for NAND flash, but in case of SSD its abstracted away, especially if drive implements compression.
I actually meant blocks on the file system level, meaning that you don’t have to rewrite the whole MP3 file once the play count field is there. Of course that might still mean that more has to be rewritten on the flash storage level, but that would be independent from the MP3 file size.
Modifying files in place seems to be very rare outside of OS. Do you know of any every day programs doing it other than actual disk editors? Not even Hex Editors get it right.
HxD will modify file in place one character at a time, that is individual WriteFile commands per byte. Depending on write caching policy modifying 100KB of a file has a chance of generating 100K*(cluster size) total written bytes to SSD.
Frhed DGAF and replaces whole file in place from offset 0 no matter the size of a file, offset of edit or size of edits.
The safe way nowadays is write new file, rename, delete old one. Best case scenario you get appends.
> Modifying files in place seems to be very rare outside of OS.
It’s difficult to tell how common it is, but it is trivial by either using seek() and write() or by mmap()-ing a file. I’ve done the former for the purpose of simulating virtual memory to work with multi-gigabyte data structures in 32-bit memory space. Dropbox does it when syncing changed blocks within a file. Databases usually do it.
