Network transfer speeds using cp?

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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