Keepalives, ChangeNotify & ISDN

Panu Outinen Panu.Outinen at
Wed Apr 28 11:34:56 GMT 1999

Hi there!

The latest Samba branch (2.0.x) supports now the ChangeNotify concept that
makes Samba send file changes in the current directory back to the
requester e.g. Windows Explorer. Most of the time this a nice feature but
with ISDN connection this keeps popping up the long-distance (=costly) line.

I've managed to circumvent this by using the following (in the host
dependent smb.conf file!) for NT4.0 hosts behind ISDN line (2592000 = 1

change notify timeout = 2592000

I just wonder if the code could be changed to accept value 0 to mean NOT to
use change notifies at all ????? 

With another project I just discovered that these change-notifies are a
major bottleneck between two NT 4.0's if one copies file (by doing 8kB
write()'s) to another and have at the same time a Windows Explorer window
open in the same directory!!! The performance drops to 1/10 of the maximum
throughput, in another words it took 7-10 times as long to copy the file!

Another thing concerning ISDN. The SMB's keep alive option is NOT 0 by
default (like the documentation in smb.conf says this sould be fixed!!!)
It's 300 seconds if one checks the source code! Also in the code TCP/IP's
SO_KEEPALIVE option gets set by default (was it once every 2 hours the
default value for the dead end checking in NT?). So for the ISDN hosts I
have used the following special settings:

change notify timeout = 2592000
keep alive = 0
socket options = TCP_NODELAY SO_KEEPALIVE=0

Panu Outinen                           Tel. +358 3 313 411
Vertex Systems Oy                      Fax  +358 3 313 41450
Vaajakatu 9                  
33720 Tampere, FINLAND                 email: Panu.Outinen at

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