Slightly OT - SFTP versus FTP speeds

Steve Flynn anothermindbomb at
Thu Sep 24 10:14:44 UTC 2009

On Thu, Sep 24, 2009 at 11:06 AM, Steve Flynn <anothermindbomb at> wrote:
> I know many of you use SSH to securely leap from machine to machine.
> How many of you utilise SFTP and vanilla FTP though? If you do, what
> kind of speed difference do you witness in throughput?
> I ask because the current environment I'm working in (a clients site)
> is seeing quite large differences in throughput between two machines
> (on in the UK, another in the states). The circuit connecting the two
> is a private circuit, no other traffic on it during our testing
> periods. I am seeing a 100Mb file or Lorem Ipsum text being
> transferred at up to 4.4Mb/s (which is about as fast as we'll get it
> to move as the slowest part of the circuit is about 5Mb/s.

Damn - hit send accidentally.

As I was about to say, vanilla FTP hits around 4.4Mb/s.

The same file, over the same circuit when being sent via SFTP
(Blowfish encryption, compression off) manages a rather disappointing
300 K/s.

I'm well aware that encrpytion is going to cause a reduction in
throughput but I'm having a hard time convincing the network engineers
that a drop from 4.5 meg per second to 300 K per second is
considerably more than I would expect.

Anyone out there got similar results I can compare against.

Processing power is not an issue - one end is a Windows VM machine and
the other end is a pretty heft AIX server. The two are obviously
running different implementations of the encryption stack (OpenSSH on
AIX, not sure about the Windows VM machine). We are about to begin
trying different SSH stacks on the Windows machine to rule out any
oddball incompatabilitis  but if I can get some indication that the
results I'm seeing are "off" then I'd appreciate it.

When one person suffers from a delusion it is insanity. When many
people suffer from a delusion it is called religion.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

More information about the ubuntu-users mailing list