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Which are the scenarios  where the Mediator can trigger a site failover MAUSO?

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Applies to

  • MetroCluster IP
  • Mediator
  • Automatic Unplanned Switch Over (AUSO)

Answer

The following table describes the different disaster scenarios and corresponding actions taken for MAUSO: 

 

mccip_auso_med.jpg

 

 

Disaster Scenario AUSO triggered? Notes

Power Outage of All Nodes
NvLog in sync before disaster
Mediator is online

 yes This condition will be detected about 15 seconds after the last node is down
All the nodes panic at site A
NvLog is in sync
Mediator is online		 yes AUSO will be triggered soon after the last node panics.
All nodes halted on site A no Nodes are expected to be started by the user.
All nodes rebooted on site A no Nodes are expected to come up, no AUSO is triggered.
A1 takes over A2 gracefully
Disaster at site A
NVlog in sync before disaster		 no  
A2 panicked
A1 does a takeover of A2
Disaster at site A		 yes Site B will use the mediator disks to establish quorum and trigger switchover
Diaster at site A
Mediator not accessible on site B		 no Manual switchover will be required
NvLog not in sync on site A
Disaster at site A		 no  
SFO is disabled on siteA A1 is down
Nvlog in sync on site A
Disaster on site A		 yes Site B will use the mediator disks to establish quorum and trigger switchover
SFO is disabled at site B
B1 is down
Disaster at site A		 no DR-AUX mailbox is not available, hence AUSO cannot be performed.
Note: AUSO can be supported if mailbox can support DR-AUX instance using the mediator disk
On node A1, both ISLs fail and mediator is not accessible no A1 is halted. A2 will takeover
B2 is down, B1 in takeover.
Disaster at site A		 no  
A2 is down, A1 in takeover.
B2 is down, B1 in takeover.
Disaster at site A		 no DR-AUX mailbox is not available, hence AUSO cannot be performed.
Note: AUSO can be supported if mailbox can support DR-AUX instance using the mediator disk
SFO is disabled at site A and Site B
node A1 and node B1 is down
Disaster at site A		 no DR-AUX mailbox is not available, hence AUSO cannot be performed.
Note: AUSO can be supported if mailbox can support DR-AUX instance using the mediator disk

Both ISLs failed. Mediator connection online.

 no Nodes will stay alive.
Site A isolated with both ISLs and mediator connection failure at the same time yes Site B will obtain the mediator lock and do switchover. Site A will commit suicide.
Both ISLs failed on site A
Then, mediator failure		 no AUSO is not possible due to loss of quorum. Nodes will stay online.
Both ISLs failed on site A
Disaster on site A
Nvlog is in sync		 yes Site B will use the mediator to determine that site A is down and then initiate a switchover.
Both ISLs failed on site A
NvLog out of sync
Disaster on site A		 no AUSO not possible. Manual intervention required.
Mediator is deleted
Disaster at site A		 no AUSO is not possible. Manual switchover will be required
On node A1, mediator disk failed
After sometime, A1's remote mailbox disk failed		 no

AUSO will be disabled. Node can remain online
Both site A nodes lose access to mediator, then disaster at site A no AUSO is disabled after mediator failure. AUSO won't happen after disaster
Mediator disk failed on one or more site A nodes.
Mediator disk access restored. Disaster on site A		 yes AUSO will first be disabled. Then, after restoring mediator, AUSO will be automatically enabled.

 

Additional Information