In windows 11, NTFS file system hdd or ssd,
Suppose that there is a very large .iso file, for example 200 GB.
That .iso file contains only data files (like music, text, documents..) and not bootable.
And I want to add some small number of files to that large .iso,
without extracting it or re-compressing it.
So that
it takes very little time,
no large free disk space is required.
Unfortunately, adding files to a .ISO file (https://en.wikipedia.org/wiki/ISO_9660) always requires recreating the entire file.
They are optimized for a physical CD or other optical storage, with sequential access and no wasted space. Adding any files requires adding some bytes at the beginning of the .ISO where it describes each file's location. This means all the other existing files have to get "pushed" about that many bytes further as well, meaning the entire thing gets re-written. It's the same for removing any files too - proper .ISO files don't have any empty space, so it's not as simple as just removing that data.
More modern disk image formats like VHD or VMDK are not sequential and can be edited more directly (but are terrible to use with CDs).
