[Samba] ok, so oplocks: good or bad?

[Jonathan Johnson]

OK, I don't have a strong understanding of oplocks, but I'm sure someone
will correct me where I go wrong.

Overgeneralization #1: Disabling oplocks is ALWAYS a safe thing to do.

Overgeneralization #2: Oplocks provide a performance boost by allowing the
workstation (ws1) to cache a copy of the file locally and set an oplock.
This way, the ws1 can assume it has exclusive access and doesn't need to
read/write to/from the server for every operation. Occasionally, the ws1
syncs the cached copy with the server copy. When another workstation (ws2)
requests access to the file, the server asks the ws1 to break the oplock.
Ws1 then syncs the cache with the server, and tells the server that it's
released the oplock. The server then tells ws2 it can access the file. If
ws1 has the file open for read (not write), ws2 can open the file for read
without breaking any oplocks.

Overgeneraliztion #3: With oplocks disabled, the workstation must always ask
for an exclusive lock before writing to the file, and does not cache a copy.
Another workstation can't access the file until the first workstation
releases it.

Exactly what goes on when things go wrong (server doesn't ask for oplock
break; workstation doesn't release oplock, etc.) I can't tell you. As for
the meaning of your errors, I haven't a clue.

--Jon

P.S. -- My philosophy is that if you ask a question and no one answers, tell
a lie as gospel truth and everyone will.

On 20 Jun 2003, Mark Roach wrote:

> I have been searching for info on this and haven't found an
> authoritative answer. From what I have read, oplocks are good because
> they increase connection speeds, but they are bad because they don't
> really work, but they actually do work, but they only work in some
> cases, etc etc.
> 
> so, here's my problem and my question together: I get tons of these
> messages every day (over a thousand a day)
> 
> [2003/06/20 08:19:42, 0] smbd/oplock.c:request_oplock_break(1011)
>   request_oplock_break: no response received to oplock break request to
>   pid 22335 on port 35010 for dev = 2b00, inode = 688540, file_id = 256210
> [2003/06/20 08:19:42, 0] smbd/open.c:open_mode_check(652) open_mode_check:
>   exlusive oplock left by process 22335 after break ! For file UHG/Local
>   Settings/Temporary Internet Files/Content.IE5/desktop.ini, dev = 2b00,
>   inode = 688540. Deleting it to continue...
> 
> 
> is this an indication that I should disable oplocks, or is disabling
> oplocks a foolish, unsafe thing to do, or is there just some other
> problem I need to fix to allow me to keep using oplocks?
> 
> Very confused.
> 
> -Mark
> 
>