Why is rsync 2x faster than sftp?

Question

I'm transferring huge files, over a network to a destination server, totaling ~ 67 GB with individual zip files of size ~ 7GB. I tried copying to the destination using both sftp and rsync. rsync performs (2x) faster copying than sftp. sftp was achieving around 700 kbps while rsync transfers the data at a rate north of 1.4 Mbps. I know that SFTP and SCP uses the same SSH connection for transferring files. So, does this imply rsync is much (2x) faster than SCP which uses SSH under the hood?

Or above all, is there an even faster way to transfer (such huge) files over a network?

P.S.: I'm transferring completely new data to the destination server with the following rsync command:

rsync --info=progress2 -az source_folder username@destination_server:/location/

Solution

Or above all, is there an even faster way to transfer (such huge) files over a network?

You can speed up scp with

scp -p -C -o 'CompressionLevel 9' -o 'IPQoS throughput'  -c arcfour machine:file .

I saw up to 5 times better speed using scp but of course external factors play a big role here.

Comments

[muru]

Is rsync connecting using SSH? Are you just updating data or is this transferring entirely new data? What options did you use for rsync?

[kmario23]

@muru please see my updated question!

[muru]

So you're using compression -z. Try without it.

[kmario23]

@muru On average, the transfer speed is same whether I use compression -z or not :(

[Admin]

Do you mean sftp or scp? scp is known to be slower because it requires more overhead.

[kmario23]

I'm getting command-line line 0: Unsupported option "compressionlevel" and Unknown cipher type 'arcfour' errors while trying your suggestion

[kmario23]

Also, I found exactly same answer here: superuser.com/a/787479 . Not whether this answer was copied from this link