The timestamp check isn’t as good.  When rsync decides to transfer a file, it 
does so by just sending the parts that have changed.  (Like running a 
diff/patch, but it works on binary files as well.)  The result is very little 
data is actually transferred for files that just have small changes.  

I did a little experiment: I’m running the belchertown and seasons skins.  In a 
typical cycle, rsync “transfers” — updates — 1.2-1.3MB of files.  The total 
data actually flowing on the network between the two machines is only half of 
this, 650K, and that includes all the handshaking, protocol overhead, file 
metadata, and even the SSL setup — everything above the TCP layer.  The update 
includes 340K of webcam jpegs that most likely have to be fully copied each 
time, so the remaining 1MB is updated with only 300K of network traffic. 

As invoked by weewx, rsync makes the update decision by looking for changes in 
file size and modification time.  Rsync has an option to make the decision by 
comparing checksums.  I tweaked rsyncupload.py to use this, and found that it 
didn’t make a significant difference in the amount of network data.  Apparently 
the contents of most of the files really does change.

  -Les



> On 9 Mar 2021, at 7:13, Ryan Stasel <[email protected]> wrote:
> 
> Wow. That’s unfortunate. FTP works great and has for a while for me! Adding 
> the time stamp check would probably have the same results as rsync I would 
> imagine. 
> 
>> On Mar 9, 2021, at 06:54, Karen K <[email protected]> wrote:
>> 
>> [email protected] schrieb am Dienstag, 9. März 2021 um 15:45:26 UTC+1:
>> Can you SSH to your host?
>> 
>> Unfortunately, no.
>>  
>> 
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