samba - Jul 2007 - Samba Problem With Big File Transfer on Windows Client

I use fedora 7 and the last stable version of samba 3.0.25a-3
on an embedded linux system as a server and a windows xp.
I 'am using truecrypt and sharing de mount directory with the XP machine via
samba. Selniux is disabled.

Everything works well such as connection or small files transfers but we
have a
huge problem when we try to transfer a big file (~100 MB) from the client
(Windows) to the server (embedded linux). No problem in the other side.

Indeed, windows displays an error saying that "the specified network name
is
no
longer available".

Moreover, we have performed different kinds of tests such as using a Linux
client or using a Linux PC as a server (with a Windows client) and
everything
goes right. We assume that our problem comes from our Linux Embedded system
but
we cannot find out the critical point. Moreover logs messages do not give us
more information execpting the "oplocks" problems, which are not the
problem
origin.

Thanks
NP

>>>problem when we try to transfer a big file (~100 MB) from the client
>>>(Windows) to the server (embedded linux).
I had encountered a similar while copying the larger file from client to
server. I had figured out that this causes due to failure in extending the
file using ftruncate call.

While copying a file from client to the server, server first extends the
file up to the file size by executing the ftruncate() and writes 0 to the
extended area. If the file is huge say in your case 100MB the client times
out by the time ftruncate returns after extending the file.

The code this happens in samba is in below module:

/smbd/vfs-wrap.c

int vfswrap_ftruncate(vfs_handle_struct *handle, files_struct *fsp, int fd,
SMB_OFF_T len)
{

...
 result = sys_ftruncate(fd, len);

....

}

To confirm whether this is the problem you can write a small program to see
whether ftruncate is taking a lot of time. Also you can capture packets and
see where exactly the problem is?

HTH

Aravind

Hi
After your sugestion i have been testing samba with the options keepalive,
dead time, debug level = 4, but the final result was the same apparently,
even the logs dont show any useful information.
During the test i notice a peak in the CPU usage bye the process
"pdflush"
and "smbd". I think pdflush is a kernel process dont konw if this
helps to
identify the problem origin.
Aravinda Guzzar thanks for the sugestion on the ftruncate function and the
packets situation, but i dont think i have the know-how  to do it

thanks
NP