[Samba] Client link utilization

[Stan Hoeppner]

Bostjan Skufca put forth on 2/6/2010 6:14 PM:
> Hello everybody!
> 
> This is probably going to be a classic question but I cannot find a
> decent answer on net.
> 
> I have samba server set up and the following things work flawlessly:
> - iperf shows 92% link utilization
> - FTP/SCP/HTTP transfers work in 10MB/s range.
> 
> However, when I mount samba share with linux client (mount.cifs) the
> link utilization cannot bypass cca 33%. Transfer speeds constantly
> stops around 3.8MB/s and will not rise above it no matter what socket
> and locking options I use.
> 
> Do you have any ideas about why this is happening and/or FAQ websites
> to point me to?

I've had a similar thread running for a few weeks without resolution.  In my
case I can max the wire (100FDX) at 92Mb/s to/from Win2K and WinXP clients using
FTP, and smbclient from the server to shares on the workstations maxes the wire
(at least GET from the workstations does).  I'm running Samba 3.2.5 on Debian
Lenny with custom kernel 2.6.31.1.

The max smb performance I can get in a single stream to/from smbd is 65Mb/s, or
8.5MB/s.  I've now tested Win2K, WinXP, and smbclient on SLED 10 (can't recall
version).  In all cases, no matter what performance settings I tweak in smb.conf
or on the workstations, I can't get wire speed with a single SMB stream---can't
get over 65Mb/s.

Interestingly, two simultaneous SMB transfer streams (two Windows Explorer file
copy operations on the same workstation) will max the wire at 92Mb/s, or 11MB/s.

Our symptoms are similar, though we may be fighting different causes, given you
can't even get over 4MB/s.  I've provided multiple packet captures as
instructed, but haven't heard anything back yet.  That was over a week ago...

-- 
Stan