[Samba] high network traffic

Thierry ITTY thierry.itty at besancon.org
Tue May 10 08:24:54 GMT 2005


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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