Mass software update distribution + checksum-updating

Gavriel State gav at
Mon Jul 9 06:13:36 GMT 2007

Hello Rsync devs,

We're investigating ways to provide large scale software updates for 
multi-gigabyte games, and have recently begun to explore whether rsync 
may fit the bill.  In particular, the checksum-updating patch looks like 
it might be able to solve our biggest concerns about CPU load on the 
update server, since the actual content being served will change quite 

Would an rsync server running 3.0 CVS + the checksum-updating patch 
still retain the precomputed checksum advantage when talking to an older 
2.6.9 client?  Or would a 3.0 client be required on both sides?

Alternatively, would it be difficult to backport the checksum-updating 
patch to a 2.6.9 server?

Lastly, does anyone have any empirical data on how well an rsync server 
with checksum-updating works with large number (eg: hundreds to 
thousands) of simultaneous clients?  If not, we'll be happy to provide 
some data from our own testing if we do end up going down this path.


Gavriel State 
Founder & CTO
TransGaming Inc.
gav at

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