Very bad performance when copying large files from windows to samba-share

Esh, Andrew AEsh at
Fri Apr 12 06:54:02 GMT 2002

I've tested files at the 4G limit, back when there were a few issues with
that size. All known issues were fixed, and tests I have seen regularly
store files larger than 4G on Samba.

I also have a lot of experience with Win98. There is a performance problem
which is difficult to produce, but large files should still be copied,
albeit slowly. To avoid the performance problem I am speaking of, make sure
you mount the share using the IP address of the host, and not its name.

It sounds, to me, that your Samba daemon may be having some other problem.
The disk activity with no network activity could be a core file being
written. Set your debug level to 10, copy the same file, and have a look at
the tail end of the logs.

-----Original Message-----
From: Lars Heineken [mailto:Lars.Heineken at]
Sent: Friday, April 12, 2002 8:35 AM
To: samba-technical at
Subject: Very bad performance when copying large files from windows to

Hi !

I'm searching for an answer to this problem for a while, maybe this is the
right place for help ?

I share my drives with samba, (smb.conf is nearly unchanged from default).
Lately my brother tried to move a 780MB file onto one of my shares. As samba
is working fine with all other files, I thought everything would work fine. 

It didn't.

So here's the problem:
No Windows-client can copy files larger than about 700MB onto one of my
shares. The moment the transfer starts, no popup-window appears on the
windows-screen, but my disk begins heavy writing, even no single packet is
floating through the network. After about 30seconds the connection times
out. The copied file can be found on my share but it's empty.
The logs say something about oplocks, but as I turned them off for a test
nothing changed.
When my brother maps the drive and copies the file inside the DOS-box,
everything is fine.
It seems that the win98 explorer has some kind of bug, that tells him to set
up an empty file before he starts writing.

As there must be a way to copy large files from windows to a samba-share,
I'm seeking someone who has solved this problem.


Lars Heineken.

PS: I read the man page about smb.conf and all switches that could have an
effect are set up correctly by default. Running version is 2.2.3a-10mdk.
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