[Samba] performance problem with windows 2003 client

Stephen Roylance sdr at sroylance.com
Fri Dec 14 20:17:19 GMT 2007

I've run into an odd (at least to me) performance issue between a samba 
server and windows 2003.  The windows side is w2k3 w/ SP2 on an HP DL585 
with HP EVA SAN storage.  Linux is CentOS 5 on a Sun X4200 with samba 
package samba-3.0.25b-1.el5_1.4and a FUSE mounted filesystem 
(glusterFS).  Watching the network tab of task manager while pulling a 
few large files from the samba server to the fast drive on the windows 
end I see an oscillation between 50% (of gigabit) and 0%.  A trace 
captured on the linux side and analyzed in wireshark corroborates, 
periods of high throughput alternating with periods of near-inactivity.  
The periods are roughly of equal length, usually between 4 and 8 
seconds.  As far as I can tell during the slow periods windows slows 
down on sending ACKs and issuing andx requests, it looks like samba 
continues to answer requests quickly, but windows doesn't send them at 
the same rate.  I don't see the TCP window dropping to less than the 
size of a frame at any time.

I assume this is windows client-side behavior, I'm not even sure if it's 
samba-specific at all, but I don't have any windows file server that I 
expect would be able to push 50MB/s consistently to test against.  I get 
close to 60MB/s using a CIFS mount locally on the samba server.

Any suggestions or recommendations would be appreciated.

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