[kwlug-disc] Transferring large backup files over the network

[Remi Gauvin]

On 2019-05-24 12:30 a.m., Paul Nijjar via kwlug-disc wrote:

>> The other key point that was mentioned, but I re-iterate since it is
>> important, is to copy files as
>> a whole, and not bother to checksum them.
> 
> Even for large (20GB) files with only small changes? I thought this is
> exactly why you would want the checksum/diff algorithm. even if you
> have a relatively fast network.

Not unless your network speed is significantly slower than your disk speed.

If rsync has to create a delta, first, the complete file has to be read
on both source *and* destination, differences calculated, then the file
has to be completely written on the destination, (unless using
--inplace, but that has it's own special considerations.)

If you're on a Gigabit network copying from/to a hard drives it would
have been faster just to copy the whole file from the get go.



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