[Samba] An Interesting Issue in Samba Performance

[Jeremy Allison]

On Fri, Jul 30, 2004 at 06:12:13PM +0100, Nicholas Butler wrote:
> Okay Ive had a day of it today , and I thought I would share this little 
> support event experienced today.
> 
> A Client site of mine runs Samba 2.2.8a connecting to a series of 
> Windows XP boxes via a Netgear Switch/Hub.
> 
> Earlier in the week they reported that certain applications, most 
> notorously Symantec ACT were performing at super slow speeds.
> 
> A non site investigation showed that any file opened from the Server , 
> copied to the desktop client was being copied at super slow speeds, as 
> if all the bandwidth on the network had gone.
> 
> Checking configuration of the smb.conf and local machines proved no use 
> at all and for a part of the hour I scratched my head as I tried to 
> understand what was slowing down all file open, copy and move 
> performance over the network.
> 
> Since local file activity ( on the server or client ) was more than 
> adequate I was non plussed, until I reasoned that the only other device 
> between Client and Server was the Network Switch.
> 
> A Quick power cycle of the Netgear switch later , and the performance 
> was back where it should have been !
> 
> Just a  salutory tail to tell really  since the problem was neither 
> Server or Client based, but the architecture was clearly malfunctioning.
> 
> Does anyone know of a test I could have carried out in order to trouble 
> shoot that particular issue ?

When I used to work on problems like that for Vantive all I did was
put a sniffer on client and server and look for dropped packets. Once
I found one or more on a lan segment I knew there was an equipment
problem. Few people bother to do this these days - even though the
lan equipment has got cheaper (and worse) than it used to be.

Jeremy.