solidDB Help : Samples : HotStandby sample : Watchdog sample application : Failure situations and watchdog actions : Communication links with the secondary server from both watchdog and the primary server are down
  
Communication links with the secondary server from both watchdog and the primary server are down
Scenario
The connections to the secondary server from the watchdog and the primary server are broken.
Symptoms
The watchdog poll of the primary server fails. The secondary server and primary server have lost their connections to each other; therefore the secondary server is in SECONDARY ALONE state, and the primary server is in PRIMARY UNCERTAIN state.
Note If the AutoPrimaryAlone parameter is set to Yes in solid.ini, the primary server switches to PRIMARY ALONE rather than PRIMARY UNCERTAIN and continues to accept transactions.
Remedy
The primary server can continue operations even when links to the secondary server and the watchdog are down. Switch the primary server to PRIMARY ALONE state (if the primary server is not already in PRIMARY ALONE state). When the network connections are recovered, synchronize the servers.
 
Description
Illustration
When the servers cannot connect to each other, Server #1 switches to PRIMARY UNCERTAIN state and Server #2 to SECONDARY ALONE state.
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Because the watchdog cannot connect to Server #2, the watchdog concludes that Server #2 is not available and switches Server #1 to PRIMARY ALONE state by using the command:
ADMIN COMMAND 'hsb set primary alone';
Note If the transaction log on Server #1 fills up before the network connection is fixed, you might have to switch Server #1 to STANDALONE state.
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The administrator fixes the network connections.
If the transaction log on Server #1 has not filled up, the watchdog instructs Server #1 to connect to Server #2 by using the command:
ADMIN COMMAND 'hsb connect';
Server #2 reads the transaction log from Server #1.
Note If you switched Server #1 to STANDALONE state, you must copy the database from Server #1 to Server #2 before you reconnect the servers, see Synchronizing primary and secondary servers for details.
The diagram is described in the first column of the row
Further scenarios where communication links with the secondary server from both watchdog and the primary server are down
If an application receives error message 10047 or 14537 from the primary server:
▪ Try to connect to the original secondary server to check if the server is now the primary server.
▪ If the original secondary server is not the current primary server, re-execute the transaction with the original primary server in PRIMARY ALONE state.
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Failure situations and watchdog actions