VMS Help V73 Features, System Management Features, CPU Online Replace (Alpha)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    With OpenVMS Alpha Version 7.3, you can replace secondary CPUs on
    a running system without rebooting, which provides increased
    system maintainability and serviceability. This feature is
    supported only on AlphaServer GS160/320 systems. Note that
    replacing the primary CPU requires rebooting.

    To use this feature, you must first download console firmware
    Version 5.9B from the following location:

    http://ftp.digital.com/pub/DEC/Alpha/firmware/

    You can then use the following DCL commands to replace a CPU
    without rebooting:

    1. Direct OpenVMS to stop scheduling processes on the CPU:

       $ STOP/CPU n

       (n is the number of the CPU to be stopped.)

    2. Power off the running CPU:

       $ SET CPU/POWER=OFF n

    3. When the light on the CPU module has turned from green to
       amber, physically remove the CPU module from the system. Then
       put in a new CPU.

    4. Power on the CPU:

       $ SET CPU/POWER=ON  n

    OpenVMS automatically adds the CPU to the active set of
    processors.

    Note that the Galaxy Configuration Utility (GCU) also supports
    this capability.