samba - Dec 2004 - Speed of Samba through VPN

Hi there,

Recently, I successfully set up an RHEL3 server running Samba over a 
PPTP VPN connection, however, the client is complaining about access 
speeds. The problem is not so much opening the files, but browsing the 
folders - however, this only appears to be slow from the client end, not 
mine.

Today, we ran a quick test which compared the volume of traffic sent 
over the VPN connections to the central server from a client machine and 
from my test machine. We found that the volume of data being sent and 
received during the process of opening a shared folder, seeing the 
contents appear, then opening a subfolder and seeing its contents appear 
was approximately three times as much on the client machine as my test 
one. Does anyone know why it should be the case that smb is sending and 
receiving three times as much data to one machine using a share as another?

The test machines are both running Win2K SP4, have exactly the same VPN 
connection settings and offline file settings (turned off for this 
resource). The machines are at different locations using different 
connection technologies to reach the internet - could this be effecting 
the volume of traffic sent and received by smb?

I have followed some of the discussion regarding the use of Samba 
through a VPN connection and from the posts earlier this month, I can 
see that Apache and Davenport look like better long term solutions, 
however, we won't be able to implement these until the new year - so 
help on a short term solution would be really appreciated.

All the best,

James

> Today, we ran a quick test which compared the volume of traffic sent 
> over the VPN connections to the central server from a client machine and 
> from my test machine. We found that the volume of data being sent and 
> received during the process of opening a shared folder, seeing the 
> contents appear, then opening a subfolder and seeing its contents appear 
> was approximately three times as much on the client machine as my test 
> one. Does anyone know why it should be the case that smb is sending and 
> receiving three times as much data to one machine using a share as another?
Are you talking about raw packet count, packet size, or just content?
If either of the former, yes, the count and total transaction size will
be larger.  Your VPN connection is probably using a much smaller MRU/MTU
than your LAN,  resulting in more overhead (packet headers, etc..)
> The test machines are both running Win2K SP4, have exactly the same VPN 
> connection settings and offline file settings (turned off for this 
> resource). The machines are at different locations using different 
> connection technologies to reach the internet - could this be effecting 
> the volume of traffic sent and received by smb?
Yes, check the MRU/MTU.

Hi,

James Cooke typed:
> Recently, I successfully set up an RHEL3 server running Samba over a 
> PPTP VPN connection, however, the client is complaining about access 
> speeds. The problem is not so much opening the files, but browsing the 
> folders - however, this only appears to be slow from the client end, not 
> mine.
I noticed a similar problem too, and I found that samba was sending
the DOS attributes of each folder with the read-only bit set. Windows
clients seem to check for the presence of a desktop.ini file in each
folder which has the read-only bit set. If there are lots of folders
with the read-only bit set in a particular directory, the directory
listing can take a pretty long time.

If this is the problem, you have to find some way of getting samba to
send the DOS attributes with the read-only bit reset. You could
perhaps use the option to store dos attributes in the EA. But in this
case, if the user doesn't have read access to the folders inside,
samba won't even be able to read the EA of the folder, in which case
it will generate the DOS attributes from the unix perms, which will
end up with the read-only bit set.

-- 
Mrinal Kalakrishnan  || http://mrinal.net/ || PGP:B1E86F5B ||
<mail at mrinal.net> || JabberID: <mrinal at myjabber.net> ||

Adam and Mrinal - thanks for the info.

Adam wrote>
| Are you talking about raw packet count, packet size, or just content?
| If either of the former, yes, the count and total transaction size
| will be larger.  Your VPN connection is probably using a much smaller
| MRU/MTU than your LAN,  resulting in more overhead (packet headers,
| etc..)

I found the data just by watching the windows connection status window 
(lazy) which gives the volume of data in bytes. We are comparing two VPN 
connections created from different locations piped through the net to 
the server - the VPN/SMB server is not local to either machine or 
office. I'm guessing that this windows data statistic includes the VPN 
overheads (the ppp* ifconfig stats from the server are smaller than the 
corresponding windows VPN data stats).

We'll have a go at the test again and have a look at the volume of data 
the server says it's actually stuck down the ppp connections - the raw 
transmitted data. Hopefully they will actually be equal and we can rule 
out smb and deal with MTUs.

If it turns out to be nothing to do with MTU, then we'll have a look at 
Mrinal's suggestion for why smb might be sending more info than necessary.

Thanks again for the help,

James