About rsync over SSH and compression

[JCA]

Thanks, that's very useful feedback for me, for my circumstances are likely
to be similar to yours.

On Wed, Jun 26, 2019 at 4:41 AM Brent L. Bates <blbates1701 at gmail.com>
wrote:

>      I've been doing a lot of testing of different options for both rsync
> and ssh.  For our environment, turning compression off in rsync and on in
> ssh has given us the best results.  Turning compression on in ssh gave us a
> small improvement compared to the large slowdown that compression gave us
> in rsync.  For us, we also made sure that the checksum option in rsync was
> off.  It caused a major slowdown for us.  It was doing a checksum on every
> file before deciding if needed to transfer the file.  That was killing us.
> We are transferring a wide variety of sizeed files, from small KB sized to
> GB sized files.  We are also transferring 10's of thousands of files
> between states.  I hope this helps some.
>
>
> Brent L. Bates
>
>
> On Tue, Jun 25, 2019, 12:06 PM JCA <1.41421 at gmail.com> wrote:
>
>> Rsync supports the capability of compressing data before sending. So does
>> OpenSSH. It would be probably be a waste of resources and time to enable
>> both compression capabilities at the same time, but it is not clear to me
>> whether, in general, it makes better sense to enable rsync compression or
>> SSH compression.
>>
>> My first thought would be that SSH compression might yield better results,
>> on the ground that SSH will try to cram as much data as possible in a
>> channel data message, within the limitations imposed by the maximum SSH
>> message size and the current window size. On the other hand, rsync might
>> (and 'might' is the keyword here) resort to individual
>> SSH2_MSG_CHANNEL_DATA messages for particular deltas, thus giving the
>> compression code smaller amounts of data to play with every time.
>> Additionally, SSH compression will be able to compress the rsync protocol
>> control data, which rsync will not be able to compress (right?)
>>
>> Feedback on the issues above will be much appreciated.
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>