[Samba] Client link utilization

Bostjan Skufca bostjan at a2o.si
Sat Feb 6 20:50:16 MST 2010

Yes, I've forgot to mention that I can also get link saturated with
single Win client, therefore it does not appear to be a server issue.
BTW: Slack, samba compiled from scratch (v3.4.5) and custom vanilla
kernel (but nothing fancy or unusual).


PS: The funny thing is, as I recall, I did previous samba setup 5 or 6
years ago, and I distinclty remember I was running into the same
issue, at more or less the same speed.

On 7 February 2010 04:26, Stan Hoeppner <stan at hardwarefreak.com> wrote:
> 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
> 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
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