Statistics on number of oplocks taken out on a Samba server

Jim Morris Jim at
Thu Jan 3 21:06:01 GMT 2002

Richard Sharpe wrote:

> Does anyone have any statistics on the max and average number of oplocks 
> taken out by Windows clients against a Samba server?
> Is it like 1/20 per client, 2/20, 0.5/10? Any gut feels at all?

On several small to medium sized LAN's (up to 50 active Windows 
clients), I have often taken a "snapshot" of the lock status of Samba 
using smbstatus.  I normally see no more than 10 to 20 active oplocks 
shown by smbstatus at any single point in time, even on the 50 user network.

My observations are that the use of oplocks is VERY application 
dependent.  Some proprietary database applications I have worked on code 
for can open as many as 100 dBASE files on a Samba share.  Depending on 
Samba and client settings, that could be as many as 100 outstanding 
oplocks.  Get several users running that application (written in Borland 
C++ Builder), and you can see a LOT of oplock and oplock break related 
log messages in the Samba log files, depending on the log level. 
Contrast that to a user running Word editing a document, who will only 
have a lock on the document(s) being edited.  A user just connected to a 
share or browsing it with Windows Explorer will not have any outstanding 

That said - in all LAN environments I work with, only data files are 
stored on the Samba server - applications are typically installed 
locally on the client systems. So you typically will only see one oplock 
per open file.  If the apps were running from a network drive, I am sure 
oplock use would be significantly higher.

I don't know if my highly NON-empirical data is any help, but there it 
is! ;-)

Jim Morris (Jim at

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