Network transfer speeds using cp?

[Cannon, Andrew]

Hi all,

First of all, sorry for the long post.  

A colleague of mine was performing some maintenance tests on our *nix
network when he noticed that there are variable speeds when copying to and
from Linux servers.  As a bit of background, we have a mixed Windows/*nix
network with Sun and Linux workstation connections going over a corporate
network.  The speeds listed here are for a 320MB file going across various
networks.

sun1 is a Sun Blade 150 with an IDE drive on a 100MB corporate network
(Solaris 8)
sun2 is a Sun Blade 2000 with an FC-AL disk in a different location over the
100MB corporate network (Solaris 9)
lin1 is a HPXW4300 workstation with a 10000rpm SCSI disk and is on a
dedicated 1GB Linux network with a 100MB link to the corporate network.
(RHEL 4 WS U2)
lin2 is another HP XW4300 workstation with a 15k rpm SCSI disk and is on the
same network as lin1.  (RHEL 4 WS U2)

The 'From' and 'To' columns give the names of the systems that the disks are
attached to.

'Using' tells us what system the command is being run on and the rest of the
table is fairly self explanatory.

Note that the time taken to "pull" the file from a remote system to the
local system is substantially lower on the Linux systems than the
corresponding "push" to a remote system.

Our question is, why is there such a great time difference depending upon
what you are doing with the file (push or pull) and why does an ftp push
(lin06 to lin05 using lin06) take 4 seconds compared to a 'cp' taking 995
seconds?

Is this normal behaviour or is there a way we can tweak the systems.  (Using
NFS over the network with no tweaking yet).

Any comments or suggestions would be greatly appreciated.

Andrew


Time taken to copy a 320MB file.

From		To		Using	Time			Rate
Network
====		==		=====	====			====
=======
Local copies			(elapsed secs)	Mb/s	Mb/s
------------	
work1		work1		sun1	13			197	-
work2		work2		sun2	8			320	-
worklin1	worklin1	lin1	4			640	-
worklin2	worklin2	lin2	2			1280	-

Remote copies
-------------
work1		work1		sun2	111			23	100

work1		work1		lin2	70			37	1000
worklin2	worklin2	sun1	994			3	1000
worklin2	worklin2	lin1	1329			2	1000

Network copies (push)
---------------------
work2		worklin2	sun2	844			3	100
work1		worklin2	sun1	936			3	1000
worklin2	worklin2	lin2	995			3	1000
worklin2	work1		lin2	35			73	1000
work1		work2		sun1	39			66	100
work2		work1		sun2	34			75	100

Network copies (pull)
---------------------
work2		worklin2	lin2	32			80	100
work1		worklin2	lin2	32			80	1000
worklin2	worklin1	lin1	4			640	1000
worklin2	work1		sun1	67			37	1000
work1		work2		sun2	46			56	100
work2		work1		sun1	56			46	100

ftp
===
worklin2	worklin1	lin2	4			640	1000
worklin1	worklin2	lin2	3			960	1000

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