[Samba] ridiculous slow gigabit transfer, faster with VNC

[Mark Baily]

Hi,
I have a problem with file transfers between a windows systems and unix systems.
I have one win32 desktop (intel e6400 2Gb Ram), one win32 laptop (p-m 2Ghz).
Also one linux laptop (p-m 1.4GHz) and one opensolaris desktop (intel
e4400 1GB Ram).

The two laptops have built-in 100Mbit ethernet and desktops have 1Gbit
ethernet on the motherboard. Both desktops use a Marvell Yukon.

The file transfer rate between two systems using FTP between the two
desktops (win32 to opensolaris) is consistently 50Mb/sec which is as
expected.

Using scp I only get 5Mb/sec between from any win32 system to any unix
system, much slower than expected.

Using scp from the linux lapotp to solaris desktop is 10Mb/sec as
expected (laptop has 100mbit only).

Using samba to copy a 1GB file I get about 7 minutes from win32 to
opensolaris. From opensolaris to win32 the windows dialog says
estiamted time 142 mins. Using plain FTP it takes 25sec. This is very
consistent.

A twist is that if a VNC client is open from the win32 desktop to the
opensolaris box the estimated transfer time via samba from opensolaris
to win32 drops right down to about 4 min. Much better, but still
nowhere near the FTP.

I have also tried swapping between a D-Link DGS-1008D switch and a
Netgear GS105 switch with no difference.

Since the FTP is very consistently acheiving 50megabytes/sec, I don't
think it can be blamed on a hardware fault.

However the problem doesn't appear to be just samba either, as the
slowness also occurs with scp, albiet scp is much more consistent at
5mb/sec than samba varying at 1GB/142min to 1GB/3min with VNC open.

Is this problem something to do with TCP stacks playing up? What else
might it be?

Thanks