## states_and_actions.txt Version 0.01

# Author: Frank Liepold frank.liepold@1und1.de

# Can be printed with a2ps -R --rows=1 --columns=1 -l 130 -L101 resource_states.txt
#
# Describes states and state transitions of mars entitities. Work in progress!

===================================== CLUSTER ======================================================================

action             pre-conditions                                      post-conditions
================   ==================================================  =============================================
                  
--------------------------------------------------------------------------------------------------------------------
1. create          no cluster present                                  cluster created
                   mars module not inserted                            /mars mounted
                   /mars mounted                                   
                  
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2. join            (1.) on primary host                                cluster joined                        
                   cluster not joined                                  /mars mounted
                   mars module not inserted
                   /mars mounted

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3. leave           (1.) or (2.)                                        no cluster present
                   no resources existent


===================================== RESOURCE =====================================================================

The resource states are described in resource_states.txt
In the following table the states which are of no interest in the specific
action are omitted or their values are marked with *.
The disk state "consistent" is an abreviation for not detached nor inconsistent.

HINT: The resource states are not up do date. The actual resource states are described in resource_states.txt.


action         pre-conditions                                      post-conditions
=============  ==================================================  =================================================

--------------------------------------------------------------------------------------------------------------------
4. create     
              (1.)
              mars module inserted                                role        : primary     
              device: unused                                      disk        : uptodate
                                                                  repl        : replaying
                                                                  mars_device : usable
                                                                  device      : locked
                                                                  
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5. join       
              (4.) on primary host, (2.)                          role        : secondary
              mars module inserted                                disk        : uptodate
              repl   : notjoined                                  repl        : replaying
              device : unused                                     mars_device : invisible
                                                                  device      : locked

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6. leave      
              (4.) or (5.)                                        disk        : detached
              disk: uptodate                                      mars_device : undef
                    outdated                                      device      : unlocked
                        -> wait | force
              repl: disconnected
              device: not opened by another application

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7. switch primary  -> secondary  
              (4.) or (5.)                                        role          : secondary
              role : primary                                      disk          : uptodate

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8. switch secondary -> primary
              (4.) or (5.)                                        role: primary
              no other primary host (evtl. locking (two mounts!))
              role : secondary
              disk : uptodate
                     outdated
                        -> wait | force

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9. pause_sync
             (4.) or (5.)                                         repl: paused_sync
             repl: synching
                   !synching
                        -> hint

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10. pause_replay
             (4.) or (5.)                                         repl: paused_replay
             repl: replaying
                   !replaying
                       -> hint

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11. invalidate
             (4.) or (5.)                                         disk: inconsistent

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12. logrotate
             (4.) or (5.)                                         log rotated
               
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13. logdelete
             (4.) or (5.)                                         log deleted
             logfile closed
             AND logfile received from all secondaries



===================================== DEVICES ======================================================================

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14. attach
             (4.) or (5.)                                         disk: if no "out of mars changes" occured since detach
             disk: detached                                                 state = state before detach
                                                                        else
                                                                            state = inconsistent

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15. detach
             (4.) or (5.)                                         disk: detached


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===================================== FURTHER INFOS NEEDED =========================================================

1. all state infos from remote hosts are to be provided with a timestamp indicating their actuality 

2. replication states like synching, replaying need a "progress bar"

3. useless actions (e.g. primary on a resource beeing already primary) should be handled as tolerant as possible