My Google-fu is failing me. I’m looking for store once filesystems for Linux and/or Windows. Or is store once just used for backups?
Can you be more specific as to what it is you are looking for? A file-system driver without a concept of delete – like simulating a write-once media on a regular hard drive? I believe that can be accomplished by setting permissions to not allow delete or overwrite but to allow create, but I doubt this is what you want.
I assume you know DVD-Rs exist.
Here is a WORM (Write-Once Read-Many) filesystem for Linux implemented using FUSE. FUSE (filesystem in user-space) means you don’t need to modify the kernel to install it as long as your kernel implements FUSE.
Googling for “write-once” or “write-once read-many” with other qualifiers should be useful.
Sorry, I meant filesystems in which duplicate disk blocks are only stored once but may have multiple references pointing to them. This can also be done at the file level. For example users Jack and Jill may each have the same file in their home directories so the filesystem would detect that they have identical data and physically just have one copy on disk even though each directory points to it. Like a hard link at the block level.
You might want to do a web search on “disk (or data) deduplication,” which is, I think, the generic term for what you’re talking about.
Cool, thanks. That did the trick.
Doing essentially the same thing in other contexts is called “copy-on-write”, because the data only actually gets copied when it’s modified. Operating systems like to do this with pages of RAM to make multiprocessing much, much more efficient.