/SITE=n ddcu:
       /SITE=n DSAn:

    Note: Do not include any HBMM-specific qualifiers in a command
    with this qualifier; doing so causes the command to fail.

    Indicates to the shadowing driver the site location of the
    specified shadow set (DSAn:) or shadow set member (ddcu:).

    The SHADOW_SITE_ID system parameter defines the default site
    location of the shadow set. You can override the default location
    of the shadow set with the /SITE qualifier.

    The valid range for the site location, represented by n, is 1
    through 255.

    If /ALL is specified, all virtual units are assigned the new
    value. The shadow set's member site values remain unchanged.

    After you apply this qualifier, the setting remains in effect
    until you change it using a SET SHADOW/SITE command.

    This qualifier can improve read performance because the member
    that is physically local to the system will be the preferred disk
    from which to read, provided that you specify the /SITE qualifier
    for each shadow set member and for the shadow set. (In a Fibre
    Channel configuration, shadow set members at different sites are
    directly attached to the system. For the Volume Shadowing and
    OpenVMS Cluster software, there is no distinction between local
    and remote in multiple-site Fibre Channel configurations.)