Comparison of huge files ineffective?

[Heiko Schlittermann]

Hi,


how does rsync work if it compares two very huge files on two distinct
hosts (rsync uses a networked connection, via SSH)?

Some observation seems to indicate, that rsync first reads (and
checksums?) the remote (destination) side, then, if finished, it reads
(and checksums?) the local (source) side and then starts transferring
the delta if done with the comparison of these two files on both sides.

The major problem (with respect to runtime) seems to be the missing
parellism in read (and checksumming) the source and the destination.

1)  Is this observation right?
1a) Does it depend on the rsync version?

2)  Is there a way to get read (and checksumming) of both sides
    in parallel?


    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
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