Windows has its own locking mechanism, called Opportunistic Locking, for files shared in a network environment. This mechanism is enabled by default and can contribute to file errors and performance issues in such an environment.

Disabling Opportunistic Locking on Windows Client PCs

To disable opportunistic locking on a Windows client PC, change or add the following Registry value:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MRXSmb\Parameters OplocksDisabled = 1

Disabling Opportunistic Locking on Windows Servers

To disable opportunistic locking on a Windows server, change or add the following Registry value:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters EnableOplocks = 0

Disabling Opportunistic Locking on SMB2

Opportunistic Locking cannot be turned off for SMB2, but you can disable SMB2 itself.

To disable SMB2 on a Windows Server 2008 or Windows Vista PC, change or add the following Registry value:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters SMB2 = 0

Once SMB2 is disabled, SMB1 will be used and the methods described above will be applicable in order to disable opportunistic locking for SMB1.