Always On Availability Question mark

Question

In my production environment I have two database Servers know as DBN1 and DBN2. I have made a cluster between two and DBN1 is my primary database server. Now I used Always on availability feature on both servers and databases were synchronized.

Today I am encountering an issue. There is a small question mark icon coming on the DBN1 which is shown by DBN2 always on availability properties. Moreover it is also not showing that it is a primary database. Why this is happening ?

This is my primary server output & follow the arrow

This is my secondary server output & follow the arrow

Answer 1

The secondary replica does not know the role / status of that DBN1 replica

When trying to failover to the secondary, the status of the primary is not known:

it finds the current primary replica but not the primary replica status.

When failing over from the primary it does find this information.

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When you select the properties of the replica with the question mark on the secondary replica:

Properties

Role: Unknown

Whereas on the primary replica all roles and their sync states are known.

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sys.dm_hadr_availability_replica_states

Executing this query returns multiple lines on the primary, but only the one for the secondary on the secondary replica's.

select * from sys.dm_hadr_availability_replica_states;

This behaviour would be reversed after failover.

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Extra checks

When looking at the query that gets executed when opening the properties of the unknown replica on the secondary replica, the sys.dm_hadr_availability_replica_states dmv is also used with a left join in a much bigger query.

An interesting part here is the OperationalState column:

ISNULL(arstates.operational_state, 6) AS [OperationalState],

Meaning if the replica is not present in that dmv, such as when executing on the secondary, return 6 as the OperationalState.

This state is not explicitly noted in the documentation on the dmv:

operational_state tinyint Current operational state of the replica, one of:

0 = Pending failover

1 = Pending

2 = Online

3 = Offline

4 = Failed

5 = Failed, no quorum

NULL = Replica is not local.

For more information, see Roles and Operational States, later in this topic.

The 'Unkown' state is also not noted in the documentation.

In this case 6 is used when the role is not known.

It does not always appear to be 6, when refreshing the availability replica's on the secondary:

the query used sets the unknown replica's role status to 3:

ISNULL(arstates.role, 3) AS [Role],

Which is offline on the dmv's documentation.

And the connected state column will be 2

ISNULL(arstates.connected_state, 2) AS [ConnectionState],

Which is also not noted in the documentation:

0 : Disconnected. ...

1 : Connected. ...