1. 04 Apr, 2014 5 commits
    • Steven Murray's avatar
      392b061d
    • Steven Murray's avatar
      9c49b874
    • Steven Murray's avatar
      157e2fc4
    • Steven Murray's avatar
      Added DRIVE_STATE_WAITDOWN · 5e3d60ab
      Steven Murray authored
      The state machine of tape drive in the drive catalogue of the tapeserverd
      daemon is now the following.  Please note that the actual implementation
      of the state machine is not yet complete.
      
                    start daemon /
        ------  send VDQM_UNIT_DOWN   ------------------
       | INIT |--------------------->|       DOWN       |<-------------------
        ------                        ------------------                     |
           |                          |                ^                     |
           |                          |                |                     |
           |                          | tpconfig up    | tpconfig down       |
           |                          |                |                     |
           |      start daemon /      v                |                     |
           |    send VDQM_UNIT_UP     ------------------                     |
            ------------------------>|       UP         |                    |
                                      ------------------                     |
                                      |                ^                     |
                                      |                |                     |
                                      | vdqm job /     | SIGCHLD [success]   |
                                      | fork           |                     |
                                      |                |                     |
                                      v                |                     |
                                      ------------------    SIGCHLD [fail]   |
                                     |     RUNNING      |--------------------|
                                      ------------------                     |
                                      |                ^                     |
                                      |                |                     |
                                      | tpconfig down  | tpconfig up         |
                                      |                |                     |
                                      v                |                     |
                                      ------------------      SIGCHLD        |
                                     |     WAITDOWN     |--------------------
                                      ------------------
      
       When the tapeserverd daemon is started, depending on the initial state
       defined in /etc/castor/TPCONFIG, the daemon sends either a VDQM_UNIT_UP
       or VDQM_UNIT_DOWN status message to the vdqmd daemon.  Once sent the state
       of the tape drive is either DRIVE_STATE_UP or DRIVE_STATE_DOWN
       respectively.
      
       A tape operator toggles the state of tape drive between DOWN and UP
       using the tpconfig adminstration tool.
      
       The tape daemon can receive a job from the vdqmd daemon when the state of
       tape drive is DRIVE_STATE_UP.  On reception of the job the daemon forks a
       child process to run a tape mount session.  A tape will be mounted and
       data will be transfered to and/or from that tape during the session. The
       tape drive is in the DRIVE_STATE_RUNNING state whilst the tape session is
       running.
      
       Once the vdqm job has been carried out, the child process completes
       and the state of the tape drive either returns to DRIVE_STATE_UP if there
       were no problems or to DRIVE_STATE_DOWN if there were.
      
       If the tape daemon receives a tpconfig down during a tape session, in
       other words whilst the drive in question is in the DRIVE_STATE_RUNNING
       state, then the state of the drive is moved to DRIVE_STATE_WAITDOWN.  The
       tape session continues to run in the DRIVE_STATE_WAITDOWN state, however
       when the tape session is finished the state of the drive is moved to
       DRIVE_STATE_DOWN.
      5e3d60ab
    • Steven Murray's avatar
  2. 03 Apr, 2014 3 commits
  3. 02 Apr, 2014 3 commits
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