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

[Jeremy Anderson]

Jeremy Anderson wrote:
> Hello all!
> 
> I've got a Fedora Core 3 box running Samba 3.0.8.
> It serves a variety of roles, including mail server and samba server.
> The mail server is quite fast, but the smb server generates lots
 > and lots of TCP retransmissions (as seen in ethereal).  The general
 > consensus is that this is new in the last few weeks.  One user has
 > been reporting speed problems for some time, but no metrics were ever 
gathered.
> 
> I've tried replacing the NIC, but the problem follows.  This is a
 > small network, with two 100mbit hubs, and windows 2000 on all the 
clients.
> 
> I want to suspect hardware, but flood pings from a linux box 
 > put on the network never report dropped packets.
> 
> All hosts are listed in DNS, and reverse DNS lookup is 
 > successful.  I've also configured samba to pass WINS
 > requests on to DNS.
> 
> I'm absolutely stumped.  I don't see the retransmissions
 > with anything on the network except SMB-related TCP traffic.
> 
> I don't see anything peculiar in  /var/log/messages or the 
> smbd.log file.  nmbd is running just fine.
> 
> Any assistance is greatly, greatly appreciated.
> 

I'd like to thank everyone for the help with this problem.  Replacing 
the two Ethernet hubs with a single Ethernet switch seems to have 
resolved the problem.  The two hubs were actually hot to the touch
when I looked at them.  I wouldn't have guessed that hardware would
affect just a single protocol, but it looks like only SMB was
chatty enough to overload the failing hubs.

-- 
Jeremy Anderson		jeremy (at) angelar.com	
http://www.angelar.com/~jeremy