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Re: rsync very slow, but not a network issue


Hello all,

Thanks for the help so far, on this issue with the mysterious
non-network based rsync slowdown. To recap...

Brian Dessent wrote:
Reini Urban wrote:
Alexis Gallagher wrote:
When the file is alredy there, rsync reports a speedup of about 70. (When the file is not already there, the speed up is 1, of course.) I am running rsync over ssh with pre-generated keys installed in my .ssh directories.

This is a binary MP3. rsync (as diff) is not good in checking binary diffs. Please try it with a typical text file, where the patch is smaller than the source.


That is not correct at all, and rsync would be much less useful if it
were true. rsync works with arbitrary binary data just as well as it does with text.

In any event I checked Reini's theory using a 5 MB text file that consists only of x's and newlines. So unlike an MP3, this file is non-binary and extremely compressible. And what I observed was as follows:

  scp: 348800 bytes/sec
  rsync (file not there): 303075 bytes/sec, with speedup of 1
  rsync (file already there): 733 bytes/sec, with speedup of 70

This is pretty much exactly the same problem as I was having with the
MP3 file. And I'm still quite puzzled.

Cheers,
Alexis


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