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Control automatic DFS advertisements in ONTAP with a CIFS server option

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A CIFS server option controls how DFS capabilities are advertised to SMB clients when connecting to shares. Because ONTAP uses DFS referrals when clients access symbolic links over SMB, you should be aware of what the impact is when disabling or enabling this option.

A CIFS server option determines whether the CIFS servers automatically advertise that they are DFS capable to SMB clients. By default, this option is enabled and the CIFS server always advertises that it is DFS capable to SMB clients (even when connecting to shares where access to symbolic links is disabled). If you want the CIFS server to advertise that it is DFS capable to clients only when they are connecting to shares where access to symbolic links is enabled, you can disable this option.

You should be aware of what happens when this option is disabled:

  • The share configurations for symbolic links is unchanged.

  • If the share parameter is set to allow symbolic link access (either read-write access or read-only access), the CIFS server advertises DFS capabilities to clients connecting to that share.

    Client connections and access to symbolic links continue without interruption.

  • If the share parameter is set to not allow symbolic link access (either by disabling access or if the value for the share parameter is null), the CIFS server does not advertise DFS capabilities to clients connecting to that share.

    Because clients have cached information that the CIFS server is DFS capable and it is no longer advertising that it is, clients that are connected to shares where symbolic link access is disabled might not be able to access these shares after the CIFS server option is disabled. After the option is disabled, you might need to reboot clients that are connected to these shares, thus clearing the cached information.

These changes do not apply to SMB 1.0 connections.