[scponly] Transmission times

[frank mohr]

--- Lou Piccoli <lou_piccoli at hotmail.com> wrote:

> Since moving to scponly from ftp, transmission times for the same
> amount of 
> data has tripled at best. Can anyone tell me why the increase in time
> to 
> transmit, is it because of the packet confirmations being done, are
> they 
> being done?
> 
> Example:
> to ftp 75 100Mb files it took  20hrs
> 
> to scp 75 100Mb files it takes 70+
> 
> Can someone tell me what causes?

encryption (and compression?) take a lot of processor time
you might try the same with a different crypto algorithm like
blowfish

i compared diffent transfer speeds depending on the ssh
crypto algorithm and compression/no compression
(background: someone on a different ML tried to clone
some PII systems over ssh and complained about the speed)
I tried it between a PII 300Mhz and a Athlon 2000
over 100MBit network

just digged out the results from the ML archive:

== local: 5 min 12 sec

liz:~ # date && dd if=/dev/hda5 bs=8k of=/dev/null && date
Sun Jul 24 16:57:07 CEST 2005
Sun Jul 24 17:02:19 CEST 2005

== ssh: 10 min 13 sec

frank at garfield:~$ date && (ssh root at liz "dd if=/dev/hda5 bs=8k" | \ 
dd bs=8k of=/dev/null) && date
Sun Jul 24 17:03:39 CEST 2005
1076027392 bytes transferred in 612.162889 seconds (1757747 Bytes/sec)
Sun Jul 24 17:13:52 CEST 2005

== ssh/blowfish: 9 min 23 sec

frank at garfield:~$ date && (ssh -c blowfish root at liz \
"dd if=/dev/hda5 bs=8k" | dd bs=8k of=/dev/null) && date
Sun Jul 24 17:20:50 CEST 2005
1076027392 bytes transferred in 563.366739 seconds (1909995 bytes/sec)
Sun Jul 24 17:30:13 CEST 2005

== ssh/blowfish/Compression: 23 min 46 sec

frank at garfield:~$ date && (ssh -C -c blowfish root at liz \
"dd if=/dev/hda5 bs=8k" | dd bs=8k of=/dev/null) && date
Sun Jul 24 17:31:11 CEST 2005
1076027392 bytes transferred in 1425.682706 seconds (754745 bytes/sec)
Sun Jul 24 17:54:57 CEST 2005 



		
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