This parameter is only valid when the parameter is turned on for a share. It allows the Samba administrator to selectively turn off the granting of oplocks on selected files that match a wildcarded list, similar to the wildcarded list used in the parameter. You might want to do this on files that you know will be heavily contended for by clients. A good example of this is in the NetBench SMB benchmark program, which causes heavy client contention for files ending in .SEM. To cause Samba not to grant oplocks on these files you would use the line (either in the [global] section or in the section for the particular NetBench share : An example of use is: veto oplock files = /.*SEM/ No files are vetoed for oplock grants