[Samba] max smbd processes

[Jeremy Allison]

On Wed, Jan 27, 2010 at 05:03:37PM -0600, Stan Hoeppner wrote:
> Samba 3.2.5 on Debian Lenny
> 
> From: http://www.samba.org/samba/docs/server_security.html
> "Samba is able to limit the number of concurrent connections when smbd is
> launched as a daemon (not from inetd). The 'max smbd processes' smb.conf option
> allows Administrators to define the maximum number of smbd processes running at
> any given point in time. Any further attempts from clients to connect to the
> server will be rejected."
> 
> I'm using max smbd processes for another reason.  I'm trying to optimize memory
> usage on this box, which really only ever has one samba client machine
> connecting.  I'm trying to get the number of smbd processes down to 1 but to
> this point have failed.  I have in /etc/samba/smb.conf:
> 
> max smbd processes = 1
> 
> Yet once restarting samba and connecting to a share, I get this:
> 
> [04:41:16][root at greer]/$ ps -ef|grep smbd
> root      8586     1  0 00:12 ?        00:00:00 /usr/sbin/smbd -D
> root      8591  8586  0 00:12 ?        00:00:00 /usr/sbin/smbd -D
> stan      8596  8586  0 00:13 ?        00:00:56 /usr/sbin/smbd -D
> 
> top:
>  8586 root      20   0 12368 2828 2168 S    0  0.7   0:00.12 smbd
>  8591 root      20   0 12368  984  340 S    0  0.3   0:00.00 smbd
>  8596 stan      20   0 12912 3972 2896 S    0  1.0   0:56.46 smbd
> 
> I've set max smbd processes to 1, yet I see 3 smbd processes.  Is something
> broken?

No.

> Is "max smbd processes" not an accurate description?  Would it better
> be described as "max smbd concurrent clients" or "max smbd user processes"?

Yes, that's a better description.

> I can understand the need for a master daemon process that spawns children for
> each connection, but at most that should require 2 smbd processes, not 3.  As
> you can see from the top output, only one smbd process is actually servicing a
> client.  One is completely idle, sucking up resources.  The other appears to be
> the master which spawns the children.

There's also the printer background lpq updater process, that's the
third one. We should probably update the description to make this
clear. It's all working as designed. You can always comment out
the code for this (it's in printing/printing.c:start_background_queue())
if you are resource constrained.

Jeremy.