Re: Ethernet auto-select and concurrent 10, 100 and 1000 connections

[tlaronde%polynum.com@localhost]

Hello,

And thank you all for the answers!

In order to not have to interpolate the various informations, I will
summarize:

My initial question: I have a NetBSD server serving FFSv2 filesystems
via Samba (last pkgsrc version) through a 1000T ethernet card to a bunch
of Windows clients, heterogeneous, both as OS version and as ethernet
cards, ranging from 10T to 1000T. All the nodes are connected to a Cisco
switch. The network performances (for Samba) seem poor and I wonder how
the various ethernet speeds (10 to 1000) could affect the performance,
impacting the negociations on the server auto-select 1000T card.

From your answers (the details given are worth reading, and someone
reading this should return to the whole answers. I'm just summarizing,
if I'm not mistaken):

1) The negociations are done by the switch, and the server card doesn't
handle it by itself;
2) On the server, the capabilities of the disks serving should be
determined;
3) On the server, Samba is not multithreaded and spawning an
instance for each connection, so even on a multicore perhaps not using
all the cores and even if it does, the instances are still concurrent;
4) The measure of the network performances should be determined by using
for example iperf3 available on pkgsrc.

From your questions about precisions:

For the switch:
	a) The switch is a Cisco gigabit 16 ports switch (RV325) able of handling
	simultaneous full-duplex gigabit on all the ports;

	b) The cards are correctly detected to their maximum speed on the
	switch: the leds indicate correctly gigabit for the correct cards, and
	not gigabit (no difference between 10T and 100T) for the others.

For the poor performances:
	a) On a Windows (10 if I remember---I'm not on site), with a Gigabit
	Ethernet card, downloading from a Samba share gives a 12MB/s that is
	the max performance of a 100T card; uploading to the server via
	Samba gives a 3MB/s;
	b) Testing on another Windows node with a 100T card, I have the same
	throughput copying via Samba or using ftp.

With all your help and from this summary, I suspect that the probable
culprit is 3) above (linked also to 2) but mainly 3): an instance
of Samba, serving a 10T or a 100T request is blocking on I/O, specially
on writing (sync?), the other instances waiting for a chance to
have a slice of CPU? That is, the problem is probably with caching and
syncing ---there are some Samba parameters in the config file but
the whole is a bit cryptic... And I'd like to use NFS, but Microsoft
allowing and then dropping, I don't know if the NFS client on Windows 
can still be installed without requiring to install a full Linux based
distribution...

Thank you all! once again.

Best regards,
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                       http://www.sbfa.fr/
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