[Samba] high network traffic

eric roseme eroseme at emonster.rose.hp.com
Tue May 10 19:45:10 GMT 2005

I tested W2000 and XP-SP2 on 3.0.8 on HP-UX 11i v1 (HP CIFS Server). 
All writes from 50KB file-save (notepad) were at MTU size, Samba was 
actually a little more efficient (than 2003) using about 40 fewer 
packets for the exchange.  Try testing a different app (notepad), to see 
if it is app-specific.

The file size reporting is also unknown (JFS 3.3 layout 4).  My server 
correctly lists file size over a share with XP-SP2.

An easy test is to install HP CIFS Server (it can co-exist with 
Opensource Samba) and either test it, or "smbd -b" and see how the build 
differs from yours (and smb.conf defaults).

Eric Roseme

Thierry ITTY wrote:

> hello
> I'm experiencing problems with samba (2.2.7a on linux & 3.0.15 on hp-ux)
> with windows xp (sp2) clients
> to make it short, an application reads and writes files on a share
> when the share is on a windows (2003) server, the network traffic is "normal"
> when the share is on a samba server, the network traffic is very high and
> the application response time increases very badly
> I took some traces (tcpdump, ethereal...) and I see that
> - when the file is on a windows share, the file is read or written with big
> blocks sizes (say 1000 bytes), and thus for a 50 KB file I get ca. 100
> network frames
> - when the file is on a samba share, the blocks are as small as 5 bytes
> (yes, the trace shows "read andx" 5 bytes at offset 0, then 5 bytes at
> offset 5, and so on), and the amount of network frames goes up to 20,000
> for the same file, with obvious performance degradation
> I tried various configuration changes (oplocks, raw io, case sensitiveness,
> and so on), but nothing really helps
> and more the open process looks the same with both server types : I checked
> each value and flag in the open request and answer, and only saw that one
> had the archive flag not set, and that allocation size differs ("true" file
> size for windows = 50 K, 1 MB size for hp-ux, may look as some hp
> filesystem allocation block ???), and I also saw that in both cases an
> oplock was granted.
> I have no more idea about what to do and I'd really appreciate any help

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