Disable oplocks on ReadyNAS-OS6

OS6 does not appear to have this option, at least from looking around all the settings I could find in the GUI.

Wow, that's disappointing. Not only that the new UI has a horrible usability, they even left out important features. Makes me speechless.

RAIDiator 4 only supported legacy CIFS (SMB1). We now support modern SMB2 and basic SMB3, where oplocks are not allowed to be disabled.

Does this mean you are running Samba4 now? Because Samba4 still contains the oplocks configuration parts and even the code checks whether oplocks (normal and level2) are enabled (at least in 4.1 where I checked). Maybe just an oversight?

Yes, Samba 4. It still supports SMB1, so of course the configuration parameters will still be there. But modern clients will negotiate SMB2/3.
From http://support.microsoft.com/kb/296264 (and various other places):

You cannot turn off opportunistic locking for SMB2.

We do plan to release a sort of "SMB extended controls" app, with which you can tweak more advanced settings, similar to editing the Windows registry. So when that is available (should be soon), you should be able to switch off SMB2/3 support and disable oplocks for SMB1.

Ok, that sounds great. Thanks for the update. I don't really care about SMB2 as AFAIK the main benefit is speed which is less important than data integrity. Unfortunately I have to run a badly implemented database software which simply breaks stuff if oplocks are enabled.

It looks like the app should be published within a few days. It will be called "SMB Plus".

The SMB Plus app is available now. If it's not showing up on your Available Apps list, you can grab it from here and manually install it using the Upload button.

Thanks a lot. I really appreciate this fast support.