Wasn't there a Linux file system (possibly a FUSE user-space one) that worked on writable CDs? IIRC it worked by marking the previous copy of the file as erased, and writing a new copy. On Wed, 2008-01-30 at 23:05 -0500, haskell-cafe-request@haskell.org wrote:

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PS: I would love to see an immutable filesystem that does not allow writing to files, it only creates new files and garbage collects files that have no incoming reference anymore... Just like a garbage

collected heap, and a bit like an OLAP databases (as far as I remember my DB theory...) Besides the performance bottleneck, does something like that exists?

Plan 9's venti is somewhat similar to this. though it's really a storage backend that you implement a filesystem on top of, and the fs winds up having a write cache, which is mutable in practice. The interesting thing is that the block's location is the cryptographic hash of its contents, which leads to all sorts of neat properties (as well as requiring immutability).

-- "Isn't it funny how the Global Village includes everybody but the villagers?" (http://wiki.laptop.org/go/OLPC_Publications)