Messages in this thread |  | | Date | Tue, 12 Sep 2000 11:53:16 +0200 | From | Jamie Lokier <> | Subject | Re: [ANNOUNCE] Darkstar Development Project |
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Larry McVoy wrote: > No matter what you do with rsync, there is no bloody way you can even > come close to a single 32K disk read and then a 6K over the wire transfer. > At least, I can't think of one, can you?
rsync will transfer a bunch of file modification times and, where they don't match, a bunch of checksums. This is still a few bytes of state for every file.
The obvious extension to rsync would be to make the rolling checksum hierarchical -- successively approximating smaller and smaller regions, and treating the whole set of files as a single data stream for the algorithm. "Null update" would then always reduce to transferring a single cryptographic-level checksum -- better than 6K and still works if you lose the Changeset file. :-)
> The fundemental observation is as the tree size/age grows, the amount of > change you make to it stays relatively constant but the updates grow with > tree size. One human can only make so much change, but many can make a > lot. BK takes advantage of that and does the hard work when you do hard > work, not every time you update.
Yes that's a good thing.
-- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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