Controls whether a negative name cache is used for NFS version 2 mounted file systems. This negative name cache records filenames that were looked up, but not found. The cache is used to avoid over the network lookup requests made for filenames that are already known to not exist.
0 (disabled), 1 (enabled)
In order for the cache to perform correctly, negative entries must be strictly verified before they are used. This consistency mechanism is relaxed slightly for read-only mounted file systems by assuming that the file system on the server is not changing or is changing very slowly and that it is okay for such changes to propagate slowly to the client. The consistency mechanism becomes the normal attribute cache mechanism in this case.
If file systems are mounted read-only on the client, but are expected to change on the server and these changes need to be seen immediately by the client, then use this parameter to disable the negative cache.