[lug] Throttling rsync

[Daniel Webb]

On Thu, Dec 22, 2005 at 03:22:19PM -0700, Alisdair Davey wrote:

> man rsync ...
> 
>  --bwlimit=KBPS
>  
>      This option allows you to specify a maximum transfer rate in kilobytes
>      per second. This option is most effective when using rsync with large
>      files (several megabytes and up).  Due to the nature of rsync
>      transfers, blocks of data are sent, then if rsync determines the
>      transfer was too fast, it will wait before sending the next data block.
>      The result is an average transfer rate equaling the specified limit. A
>      value of zero specifies no limit.

Rsync's option works well.  It is a little coarse, so if you want smooth
throttling you'll need to look at something else.  I know of trickle, but
lately I've had problems with it and rdiff-backup, and I'm not sure why.
trickle intercepts system calls (I think), since you use it to run other
programs "trickle -d 10 rsync / remote:/".
There's also cstream, which is like dd but with more features like stream
bandwidth throttling.  The rdiff-backup wiki has a page on how to throttle
rdiff-backup using cstream.  Anyone know any more tools that might fit?