A checksum question
jw at pegasys.ws
Wed Mar 26 05:13:54 EST 2003
On Tue, Mar 25, 2003 at 04:31:00PM +0000, Terry Raggett wrote:
> I'd like to know a little about the internals of RSYNC. I am a little
> confused as to why RSYNC is using both the simple 32 bit algorithm and
> the MD4 checksum function on the same files. From my testing this causes
> a vast overhead that is clearly not represented by RCP (fairly
> obvious!). Removing checksumming from a secure whole-file LAN transfer
> brings RSYNC in line with the general performance of RCP.
> Can someone explain to me the rationale behind the checksum algoritm and
> use within the RSYNC protocol?
> I'm asking this question as I am finding it rather difficult to convince
> some of our users that RSYNC is a viable replacement for RCP
> functionality, which is necessary to resolve some of the limitations we
> encounter with the standard RCP.
> Many thanks in anticipation,
> Terry Raggett
Rsync is not a replacement for rcp. Rcp is a remote-copy
utility. Rsync is a remote-update utility. They each exist
for completely different purposes.
Without knowing what limitations you are encountering with
rcp or to the specific purpose of use i couldn't speak to
the suitability of rsync. There are many times that rsync
is not the best or most efficient tool for the job. If all
you want is a fast light-weight copy utility, rsync isn't
it. There are even times when rsync is ill suited to an
update operation. The tool-box was invented for a reason.
J.W. Schultz Pegasystems Technologies
email address: jw at pegasys.ws
Remember Cernan and Schmitt
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