[Samba] Speed differences for windows clients

[Philipp Lies]

Hi,

we have a strange phenomenon with the transfer speed between windows 
clients and samba servers. Here's the setup:

server 1: centos 6.3 with samba 3.5.10
server 2: centos 6.4 with samba 3.6.9
both servers are configured as BDC and have - aside from netbios name - 
identical smb.conf which contains ldapsam as backend and all other 
parameters are not set (i.e. default)

When I mount a share from a linux client, the transfer speed is 
~112MB/sec to either server from any linux client. However, when I mount 
a share from Windows clients, the speed to server 1 is ~95MB/s and to 
server 2 ~85MB/s. We tested this with several windows clients (all 
running Windows 7 with all updates).

The speed difference between linux client and windows client is not 
what's confusing me but that server 2 is always slower than server 1.

Any ideas what could cause this?

Philipp