[Samba] Samba Variables and TCP/IP Throughput

[Per Kofod]

Perhaps your TCP window is too small
You should try the following global settings:

	read size = 65535
	max xmit = 65535
	socket options = TCP_NODELAY SO_SNDBUF=65535 SO_RCVBUF=65535
	

Rgds Per



AndyLiebman at aol.com wrote:
> 
> Hi,
> 
> I am trying to optimize my gigabit network. I have two Intel 1000 MT Gigabit
> Server Adapters, which support Jumbo Frames -- as well as a Switch that
> supports Jumbo Frames. However, I am observing some strange behavior in my file
> transfers from Windows XP to Linux and I am wondering if it has anything to do
> with the way the Samba variables are set on my Linux box?
> 
> The "strange behavior" is that when I set both NICs to use Jumbo Frames
> [MTU=9014 on the Windows side (includes IP headers) , 9000 on the Linux side
> (doesn't include the headers], I am getting about half the throughput that I get
> when I set both NICs to use the standard MTU of 1514/1500. I see the same
> behavior even if I take the switch out of the system and connect the Windows XP and
> Linux machines directly to each other (crossover cable not required for
> computer-to-computer connection with these NICs -- and by the way all of my cables
> are CAT6).
> 
> On the Linux side, I am using Samba 3.0.0 on Mandrake Linux 9.2 with all of
> Mandrake's current updates -- kernel = 2.4.22-21enterprisemdk. The Linux
> machine is a P4-3.06 Ghz with 1 GB of RAM -- running in hyperthreading mode.
> 
> I am wondering if any of the Samba socket options settings like tcp_nodelay,
> so_sndbuf=8192 or so_rcvbuf=8192 are affecting my throughput -- particularly
> when I am using Jumbo Frames? And are there any other Samba settings that might
> be interacting in a negative way with my TCP/IP and NIC driver settings that
> are causing me to get lower throughput with Jumbo Frames instead of higher
> throughput (which is what I am told I should be getting).
> 
> Any guidance would be appreciated. I have purchased "The Official Samba 3
> HOW-TO and Reference Guide" but it really isn't very helpful when it comes to
> understanding how to tune these options and how various socket options settings
> interact with other network settings and hardware.
> 
> Andy Liebman
> Resolute Films
> 119 Braintree Street, Suite 410
> Boston, MA 02134
> 
> Tel: 617-782-0479
> Cell: 617-308-0488
> Fax: 617-782-1071
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