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The location of the client registry entry for opportunistic locking has changed from the location in Microsoft Windows NT. In later versions of Windows, you can disable opportunistic locking by setting the following registry entry to 1:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MRXSmb\Parameters\
OplocksDisabled REG_DWORD 0 or 1 Default: 0 (not disabled) Note The OplocksDisabled entry configures Windows clients to request or not to request opportunistic locks on a remote file.
You can also deny the granting of opportunistic locks by setting the following registry entry to 0:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
EnableOplocks REG_DWORD 0 or 1 Default: 1 (enabled) Note The EnableOplocks entry configures Windows-based servers to allow or to deny opportunistic locks on local files. These servers include workstations that share files.