does partial option work over ssh?

Wayne Davison wayned at
Tue Jul 18 07:16:24 GMT 2006

On Tue, Jul 18, 2006 at 12:00:06PM +1000, Glen Davison wrote:
> In my most recent attempt, the new file began smaller than file1
> (probably at size 0, but I missed that) and has now grown to greater
> than the difference between the partial file1 and the original/source,
> which suggests to me that it is simply a whole new copy.

It's a whole new temp file, but the new file is getting its data from
the partial file instead of from the sending side.  This does mean that
this can go no faster than the amount of disk I/O necessary to copy the
data locally (if the checksum data can keep up with that).  Using the
--inplace option can speed this up somewhat because the receiving side
will just bump the seek pointer for each section of the file that
matches its per-block checksum (i.e. the transfer does still start to
perform the per-block checksums from the start of the file).  The
--append option takes an inplace transfer a step further by skipping all
the per-block checksumming for the existing partial data, and just
appending new data onto the end (though the full-file checksum still
reads the existing data, which allows rsync to verify that the final
file is indeed correct).

> Does it checksum each block, then copy that block to the temp file
> from the partial?

Yes, that's the default.


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