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As far as I can tell the only thing ZOO has over tar archives is having a history of each file (using the VMS concepts of file versions) -- meaning that it prob
by cyphar 8y ago
As far as I can tell the only thing ZOO has over tar archives is having a history of each file (using the VMS concepts of file versions) -- meaning that it probably still has some of the problems I outlined above. While that is useful, it is still not as good as it could be. Also, you don't really want file versions with container images, you want to have conceptual "layers" (which would be sort of like having versioned files but it's more like snapshot IDs -- or like ZFS's birth-times).
- JdeBP 8y agoOne needs to give it more than a superficial glance. ZOO was designed to be randomly accessible, with the directory headers forming a linked list. It actually has an uncompressed index and can take advantage of seekable files. It also supports both long and short filenames; CRCs of the metadata structures (c.f. the recent kerfuffle about xz); and an extensible, versioned, header mechanism that not only could be extended but actually already once was extended to add the long filename support amongst other things.
- cyphar 8y agoIs there an actual paper or some high-level summary of the format -- not to mention a modern implementation? The only summary I could find was the one on Wikipedia. I also found the source code of "unzoo" but it's a bit difficult to understand the benefits of a file format if I first have to understand its implementation. I didn't take a superficial glance out of laziness, it's because I couldn't find any more information about it. But I think you also missed that I mentioned that the style of versioning implemented in ZOO (as far as I can tell based on a Wikipedia page) is not the correct style for snapshot-like versioning.