Always on troubleshoot

 Scenarios where the failover not happening in Always on.

1. Port number is not allowed 1433,5022 in firewall settings.

2. Event viewer no erros found.

3. Cluadmin- Check preffered nodes in node properties.

4. check if connect permission is not enabled  for service account.

5. check alteravailability group and serverstate permission for NTAuthority/system account  on both the nodes.  (why Ntauthority/system- coz healthcheck is authorised to this account)

Failover disconnected .

1. Check Endpoint algorithm on both the nodes which must be compatible i.e AES from 2016 version or rc4 from 2014 version.

2. Check nodes are up in cluadmin.

Logins not working to connect SQL Instance.

Connect SQL SERVER instance when there is no logins working.

Sometimes we may miss password or logins not working to connect sql server in this case follow the below steps to connect the instance. 

1. Stop the instance.

2. Open CMD in Adminstator mode- Root to SQL Server bin folder  with -m which will start the sql server in single user mode.

3. Open another CMD in adminstrator mode- Run the script to set the new login or create login .

4. Exit  both CMD and start the instance.