local -> local file copy question

Justin T Pryzby justinp at norchemlab.com
Sun Aug 19 09:45:27 MDT 2012

Note that --whole-file "is the default when both the source and
destination are specified as local paths", and implies that the file
is copied without the "delta transfer" algorithm.


On Sat, Aug 18, 2012 at 11:05:47PM -0700, Linda Walsh wrote:
> In looking at source, I started at fileio and found
> write routines but no read routines.
> I found a 'WRITE_SIZE' (32K), but no 'READ_SIZE' --
> is that' what the MAX_MAP_SIZE (256K)?
> I would like to make so that rsync can use larger I/O sizes if
> (maybe a command line option?)....
> The map routine led me to receiver -- where it looks like it
> is responsible for reading the file.
> A comment says:
> "Receiver process runs on the same host as the generator process.".
> I am thinking that is the case where you are not sending to a
> a remote machine? I.e. that routine is for local copying only?
> But is that right? Generator generates sums and sends lists of sums
> to the receiving process before sending the data -- but if it is
> on the same machine, are any sum's needed?
> Then it looks like it sends all of the data through a pipe line -- even
> if it is on the same machine...
> i.e. it looks like there are no optimizations for local-to-local file
> copy?
> Is that the case?

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