On Mon, Oct 01, 2007 at 08:21:25PM -0500, Stephen Zemlicka wrote: > I thought it was supposed to do it more effeciently
Yes, protocol 30 has several improvements that reduce the number of bytes sent over the wire in addition to its incremental recursion mode. The latter is slightly less byte-efficient over a non-incremental pr.30 recursion, but is more disk I/O efficient the larger your file list gets (not to mention more memory efficient). For example, I did an rsync on a hierarchy of 30,103 files that didn't need any updates. This resulted in the following transfer counts: Protocol 29: sent 533,947 bytes, received 20 bytes Protocol 30, --inc-recursive: sent 503,658 bytes, received 676 bytes Protocol 30, --no-inc-recursive: sent 501,189 bytes, received 11 bytes You'll note that the inc-recursive mode has a little more "back chatter" due to the generator letting the sender know about its progress through the file list. Since that direction of flow is more lightly loaded than the flow from sender to receiver, the small amount of extra data should not adversely affect rsync's speed. So, the inc-recursive transfer may be slightly less efficient over the wire than pr.30 no-inc-recursive, but because the sending and receiving sides tend to be doing more disk I/O at the same time, the total transfer time can be less (depending on how much directory data is in the disk cache, how large the transfer is, and how many files need to be transferred). It would be interesting to look into applying more general compression to the file list in a future version. It would also be interesting to see if an rsync-checksum-delta technique helps out on an inc-recursive file list. I use that idea on my protocol-experiment software a while back, and it may be a net win (though it has tradeoffs, as chunks of the file list must be buffered and sorted before being delta-difference transferred to the other side, while the current code sends file list info as soon as it is scanned). ..wayne.. -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
