So I know that each file may use a bunch of clusters with each cluster having a pointer to the next cluster having the rest of the file, but I don't understand what happens when we try to delete or insert something in the middle of a file in a certain sector. How is this issue resolved in FAT?
The first Idea that came to me, was shifting the data, but that doesn't seem to be a very efficient approach.
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So I know that each file may use a bunch of clusters with each cluster having a pointer to the next cluster having the rest of the file, but I don't understand what happens when we try to delete or insert something in the middle of a file in a certain sector. How is this issue resolved in FAT?
Generally speaking, you can't delete or insert in the middle of a file, by which I mean that these operations are not directly supported by filesystem drivers. You modify a file by writing a block of data starting at a particular offset from original start of the file. You use writes to implement insertions or deletions, and this is managed at the userspace level, not the filesystem level.
The first Idea that came to me, was shifting the data, but that doesn't seem to be a very efficient approach.
There are two basic options:
you overwrite the tail of the file in place, starting at the starting position of the insertion or deletion. This is effectively a shift, yes, and the program has to manage that itself.
you write a whole new file, then replace the original with it.
The latter is usually the preferred option for modifications other than at the end of the file, because the original file remains in a consistent state throughout the process, and because you don't need additional intermediate storage for the portion of the file contents that need to be shifted.
None of this is specific to FAT. I can't rule out the possibility that there is some esoteric filesystem or storage medium out there somewhere to which different rules apply, but for the most part, this is the nature of persistent storage.