Historical Avanti cluster configurations enabled Tagged Command Queuing (TCQ) on a quorum disk. Avanti's TCQ option advertises tagged-command support to the guest and also requires disconnect support, but the claim that every OpenVMS quorum disk requires this setting has not been revalidated for Avanti 5.1.0. Follow the documentation for the installed OpenVMS release and validate the exact cluster before relying on the historical setting. See SCSI Disk [+] for the Avanti options.