[Samba] Slow transfer file between Windows and Samba PDC (2.2.3a)

[Guillaume Estival]

Hello everyone

I have a quite weird problem, and I've try a lot of possibility without
any success. It's about file transfert beetween a Windows 2000/98/ME and 
a Samba PDC. I've made some tests with a Win 2K PDC too.
Oh yes, English isn't my native language, so please excuse me in advance
for my *bad* english. 
I'll try to be the most complete I can, so this post may be a little
long.

Customer environment:
Intel(R) Pentium(R) III CPU family      1133MHz (Dell) with a Red hat
7.3 OS (Samba 2.2.3a), with 256Mo of RAM, 
scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.5 
        <Adaptec aic7899 Ultra160 SCSI adapter>
        aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs
less than 10 Windows 2000/ME/98 connected

The first problem was the crash of Excel when someone try to open a XLS
file located on the PDC. According to the log file, it's a oplock
problem (I saw posts about it and 2.2.6pre1 version, seems fixed in the
pre2, right?). I've just disabled those system. Works fine.

The Second problem is the slow transfer file between Windows (don't seem
related to the version) and the PDC. The lucky transfer rate is
8Mbits/s, which is quite slow on a full 100Mbits/s LAN. Is "mii-tool"
give true information? I've got this: 
eth0: negotiated 100baseTx-FD flow-control, link ok

Sound good, huh?
Since people there are basic end user, I can't do any other test (FTP
one, NFS one, and so on). But the funny thing is that a copy
windows<->windows is far faster (more than 2 times faster). Same Switch.

Well, STFW, see FAQ, got some infos about MTU and SO_SNDBUF stuff. I've
change the SO_SNDBUF option, and use 16384 for value. A little better,
but still slow.  I haven't found a clear information about the MTU
configuration and changes we must do for Samba. More, I read that
changing MTU under Windows 98 is quite risky, and since they are basic
end users, I don't want to risk anything (unless it's the only *working*
solution to go faster). If someone have some pointers about MTU stuff
(samba, linux kernel, windows), It may be usefull for me, feel free to
post them ;).

Well, at this point, I'm puzzled, and I can't make interesting test.
(I'm not on the customer location)
Then, since I've set up a Samba PDC at home, I've done some test here.

Home:
Laptop Celeron 366, 192Mo acts as Samba PDC
(Debian Woody 3.0), through a Xircom Ether 100/56K modem
Desktop celeron 800, 320Mo, RTL8139, Windows 98
Hub 100Mbits/s

Got *exactly* the same thing: According to iptraf, I'm stuck at 8Mbits/s
for transfer files. If I change SO_SNDBUF and use 16384, the transfer
file slow down at 3Mbits/s. uh oh. sound bad.

I'll do some other test this week end in my home configuration (FTP, NFS
transfer files) to see if this is not related to a connection problem.
(I'm not sure, but I think the NFS transfer is more likely 4MBytes/s
than 1Mbytes at home)

Here, *really* puzzled. Why samba is so slow? A weird idea comes in my
mind: What about Windows 2000, as a PDC, performances?

At work:
Duron 700, 256Mo RAM 100Mb
Windows 2000 server, acts as PDC.

Launch a 100Mo file copy on PDC. It takes 2 minutes. Uh oh?  It's less
than 8Mbits/s transfer rate... Sound strange, huh?  Well, let's test the
NAS server (Dell PowerVault 705N), it takes 40 secondes.  Sound better.
Let's try the Windows 2000 computer of my colleague: 12 secondes. Doh!

If you search "PDC slow transfer file" in groups.google.com, you'll find
a various bunch of problems, both samba PDC or Windows PDC related. But
without any clear solution.

All the file transfer have been done from a windows computer TO a PDC
computer. If I work with a big file located on the PDC, the saving is
slow too: the progress run fast, but the program is freezed until the
save is done. I use OpenOffice (at home) with a 18MB file and Word XP
(at work) with a 5MB file. I use Explorer for file transfer too, which
is better than other programs: the progress bar is real. 

Then, several questions come in my mind:
Did you ever experimented such a problem?
Is a "normal" transfer rate for a PDC?
	related: is a non-PDC samba computer run faster?
Is someone have some clues to help me pointed out the misconfiguration?
(I'm not responsible for the Windows 2000 PDC configuration, that's why
I'm puzzled with this results)
The purpose of this post is to do the right configuration for Samba as a
PDC, at decent speed, not to configure our Windows 2000 PDC (none of my
buizness, in fact)
Oh yes, Is someone, who had problems with oplock before 2.2.6, got a
working version of oplock system with this fresh version? (I don't want
to change the customer version if this is useless for the problem they
have)

Thanks in advance for your help.

here comes the relevant (I Think) pieces of configuration:
[global]
        client code page = 850
        encrypt passwords = Yes
        obey pam restrictions = Yes
        pam password change = Yes
        socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=16384
SO_RCVBUF=32
768
        character set = ISO8859-1
        domain logons = Yes
        os level = 65
        preferred master = True
        domain master = True
        dns proxy = No
        kernel oplocks = No
        locking = No
        oplocks = No
        level2 oplocks = No

-- 
Guillaume Estival