6 states of mysql-mmm and reasons for change

There are 6 states of mysql-mmm

1.online

2.admin_offline

3.hard_offline

4.awaiting_recovery

5.replication_delay

6.replication_fail

The transitions for various states are as follows:

The 1.online state is a normal state and can act as a variety of roles.

2.admin_offline is the status of manual downline

3. Replication delay can cause Replication_delay status

4. Replication interrupts (Sql_thread,io_thread) can cause Replication_fail status

5. The Replication_delay or Replication_fail status can be restored directly to the online status unless the host is set to Jitter.

6.ping is not connected and (or) the MySQL connection is interrupted, resulting in a hard_offline state.

7. If you can ping and the MySQL connection status is normal, it will become the Awaiting_recovery state.

8. Two situations can be changed from Awaiting_recovery state to online status:

A. The failure time is less than 60 seconds and has not been restarted.

B. auto_set_online > 0 Set (except for jitter state)

Reference:

ONLINE

Host is running without any problems.

Admin_offline

Host is set to offline manually.

Hard_offline

Host is offline (Check ping and/or MySQL failed)

Awaiting_recovery

Host is awaiting recovery

Replication_delay

Replication backlog is too big (Check Rep_backlog failed)

Replication_fail

Replication threads is not running (Check Rep_threads failed)

Only the hosts with state ONLINE could have roles. When a-host switches from ONLINE to any other state, all roles'll be is removed from it.

A host that's in the state Replication_delay or replication_fail'll be switched back to ONLINE if everything is OK again, Unless it is flapping (see flapping).

A host that was in the state Hard_offline would be switched to awaiting_recovery if everything is OK again. If its downtime were shorter than seconds and it wasn ' t rebooted or auto_set_online is > 0 It'll be switched back T o ONLINE automatically, unless it is flapping (see flapping again).

Replication backlog or failure on the active master not considered to being a problem, so the active master would never be I N State replication_delay or Replication_fail.

Replication backlog or failure'll be ignored on hosts whos peers got ONLINE less than seconds ago (that's the default Value of Master-connect-retry).

If both checks Rep_backlog and rep_threads fail, the state would change to Replication_fail.

If Auto_set_online is > 0, flapping hosts would automatically be set to online after flap_duration seconds.

Source Document

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6 states of mysql-mmm and reasons for change