This command allows a user to replace one tape drive behind a
    Network Storage Router (NSR) with another tape drive at the same
    Fibre Channel (FC) Logical Unit Number (LUN) location.

    This command updates all the necessary file and memory data
    structures with the WWID of the new tape drive. The name of the
    replacement drive will be the same as the name of the original
    drive.

    This command is primarily intended to be used when a hardware
    problem occurs on a tape drive, and a replacement drive must
    installed in its place.

    The command requires CMKRNL privilege. It applies only to FC
    tapes behind a Fibre Channel tape bridge such as an NSR or MDR
    (Modular Data Router).

    For more information about Fibre Channel, see the Guidelines for
    OpenVMS Cluster Configurations.

    Format

      IO REPLACE_WWID  devnam_string/WWID=wwid_string

1  –  Parameter

 devnam_string

    Specifies a tape device name.

2  –  Qualifier

2.1    /WWID

       /WWID=wwid_string

    Specifies a string that comes directly from a SYSMAN IO LIST_WWID
    display. The use of this qualifier is appropriate only under the
    circumstances explained in the description below.

3  –  Description

    You can use the two parameters, devnam_string and wwid_string,
    with the REPLACE_WWID command to replace a broken tape device
    with a new device. The command automatically updates the data
    structures that record the new devnam-WWID correlation, and the
    device automatically begins to function correctly.

    This command is useful in two different cases:

    o  In one case, the drive might malfunction and need to be
       replaced immediately without rebooting the system. If this
       happens, the drive is physically replaced with a new drive,
       and the command SYSMAN IO REPLACE_WWID $2$MGAn is issued
       clusterwide. The /WWID qualifier is not appropriate in this
       case, because the new WWID is automatically detected using
       information stored in the device's data structures.

    o  In the other case, the drive might malfunction and not
       be replaced until after the system has been shut down or
       rebooted. The device name no longer appears in the SHOW DEVICE
       display because the device failed to configure during the
       reboot.

       The configuration failure occurred either because the
       broken drive did not respond, or because the new drive has
       a different WWID from the one SYSMAN IO AUTOCONFIGURE expected
       at boot time. Therefore, in this situation, in which the
       device name is in SYS$DEVICES.DAT but not in the SHOW DEVICE
       display, use the /WWID qualifier to define the new devnam-WWID
       correlation.

       Follow these steps clusterwide:

       1. Execute the SYSMAN IO LIST_WWID command to display the new
          WWID.

       2. Use the command SYSMAN IO REPLACE_WWID $2$MGAn/WWID=new_
          wwid to define the new correlation.

       3. Use the SYSMAN IO AUTOCONFIGURE command to configure the
          device.

    When you use the SYSMAN IO LIST_WWID command, keep in mind that:

    o  You must set the replacement device to the same SCSI target ID
       as the original device.

    o  You must stop all activity on the device before issuing the
       SYSMAN IO REPLACE_WWID command.

    o  The command requires CMKRNL privilege and applies only to FC
       tapes behind an NSR or MDR.

4  –  Example

  SYSMAN> SET ENVIRONMENT/CLUSTER
  SYSMAN> IO REPLACE_WWID $2$MGA3/WWID=02000008:500E-09E0-0005-30D7
  SYSMAN> IO AUTOCONFIGURE

      In this example, the device named $2$MGA3 malfunctioned and
      was replaced while the system was down. Upon reboot, the drive
      did not get configured, because its new WWID did not match the
      WWID that OpenVMS expected. Therefore, the user redefines the
      devnam-WWID correlation and is then able to configure $2$MGA3
      correctly. The specified WWID comes from the output of the
      SYSMAN IO LIST_WWID command.