[Samba] excessive TCP retransmissions with samba 3.0, slow file opening

[Denis Vlasenko]

On Thursday 12 May 2005 17:00, Jeremy Anderson wrote:
> Thanks for the quick response, Paul!
> 
> On Thu, May 12, 2005 at 07:38:47AM -0500, Paul Gienger wrote:
> > 
> > Hubs? HUBS? I hope you meant switches. If not, go buy some switches.
> 
> 10/100 hubs.  This is a small client, with limited hardware budget.
> So, it's a pair of 8-port 10/100 hubs, connected.
> 
> > >I want to suspect hardware, but flood pings from a linux box put on the 
> > >network never report dropped packets.  
> > >
> > Then go back to hardware.  Unless you've got firewalls or something in
> > the mix that's probably where your traffic is going.  Watch the
> > collision lights on your hubs and see if they go nuts when the problem
> > occurs.
> 
> Hrm.  Good point.  Wish I'd thought of that.  I've found a new caveat, however.
> One of the machines in the office is absolutely unaffected by the problem.  It opens extremely large files very quickly.

Sounds like duplex mismatch. Flood pings tend to miss that, because ping packets
do not collide most of the time.
 
> I find that one user has been reporting the problem for several weeks, and now three more users have begun experiencing
> it in the past week.

Check this theory by verifying that all clients are half duplex.

Does this happen if you connect both machines with crossover cable
(no hubs at all)?

Use tcpdump to see the traffic on the wire.

> I cannot find any differences between the fast machine and the "slow" machines--except the fast machine has slightly older hardware than the slow machines.  All are running Windows 2000 SP4.

Please wrap long lines.
--
vda