[Samba] ridiculous slow gigabit transfer, faster with VNC

Mike 1100100 at gmail.com
Thu Jul 19 13:31:48 GMT 2007

I have noted the same behavior many times.
I have an old server box that has not been upgraded since ver. 2.2.8.
Whenever I connect from a linux box using sftp in a terminal, I get
top speed 10/100 ethernet transfer rates over the LAN -- 10 Megs/sec.
- 12 Megs/sec.
When I use WinSCP (from a win client box), I get no more than 2
Megs/sec. transfer rate.

I wish I could articulate the why, but I cannot.
But it doesn't appear to be a Samba issue, it seems to me that the
software applications we are using handle TCP data transfer very
differently and are optimized to do things very differently.

I can add some anecdotal evidence regarding VNC ---
I use RealVNC between my work winbox and a Win Server 2003 and
sometimes transfer 1 Gig. .iso files between them.  I never measured
exactly, but from memory I know it always takes at least 5 minutes
over my 10/100 LAN.  Optimally, it should require no more than 2
minutes to complete such a transfer.  I don't mean to compare apples
vs. oranges (win/linux transfers vs. win/win transfers) but I think it
helps to show it's the transfer software and probably not win, or
linux, or samba.

I hope someone else on the list with more empirical knowledge can
confirm and provide the "why".



On 7/19/07, Mark Baily <mark16829 at gmail.com> wrote:
> 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
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