--bwlimit how to

Ben Escoto bescoto@stanford.edu
Tue, 03 Sep 2002 10:26:19 -0700

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>>>>> "T" == trevor  <trevor@tecnopolis.ca>
>>>>> wrote the following on Tue, 3 Sep 2002 06:52:02 -0500 (CDT)

  T> I read in the archives how people wanted a rsync-like --bwlimit
  T> option.  I too wanted it, but am split on whether I agree with
  T> the author that it should be done outside of rdiff-backup.
  T> Theoretically he's probably correct, but practically most people
  T> will never figure out how to use cstream or the like.

I did think a bit more about this after the last discussion.  There is
an added problem that didn't get mentioned.  Right now ssh does the
compression, and the bandwidth can't be reliably limited before
compression because different data will get compressed to different
degrees.  So to add a true --bwlimit option I would have to move
compression into ssh also.  However, I've noticed that python's gzip
module is not very quick, probably because it is only partly written
in C.  Presumably ssh's compression code is much quicker.

  T> So I'm writing this email to say that I did get cstream to work
  T> with rdiff to emulate a --bwlimit type option.

Very cool.  I added this to the FAQ at


with some editing.  Tell me if you mind and I'll take it down.  I also
edited it a bit so you may want to look at it and make sure it is
still OK.

    One question though:  it looks like only ssh's output is getting
piped into cstream.  I suppose this is appropriate since the source
directory is remote.  Would the commands have to be rearranged if the
source directory is local?

Ben Escoto

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