Dynamic Services Fallback Option in Oracle 19c

Introduction of Dynamic Services Fallback:

1. A Service fails over to an available instance when there are no preferred instances available.

2. For a dynamic service that is placed using preferred and available settings, you can now specify that the service should fall back to a preferred instance when it becomes available.

3. This option allows for more control in placing dynamic database services and ensures that a given service is available on a preferred instance as much as possible.

Environment Setup:

Primary RAC         : orcl (orcl1 and orcl2)
GRID Home         : /u01/app/19.0.0/grid
RDBMS Home : /u01/app/oracle/product/19.0.0/dbhome_1
Version                 : Oracle Database 19c EE - Production Version 19.12.0.0.0

Scan IP         : oel70p-scan

Step-1: Check the status of the 'orcl' database.

[oracle@oel70-base1 ~]$ srvctl status database -d orcl

Instance orcl1 is running on node oel70-base1

Instance orcl2 is running on node oel70-base2

[oracle@oel70-base1 ~]$

Step-2: Add the service 'serv1' with 'failback' option and start the service.

Step-3: Check the status of 'serv1' service and shutdown the database, startup the database and check the status of 'serv1' service.

 

Step-4: srvctl config service does not report state of failback when it is "NO" and created new service 'serv2' checking with 'failback' option enabling and checking the configuration.

[oracle@oel70-base1 ~]$ srvctl config service -d orcl -s serv1

Service name: serv1

Server pool:

Cardinality: 1

Service role: PRIMARY

Management policy: AUTOMATIC

DTP transaction: false

AQ HA notifications: false

Global: false

Commit Outcome: false

Failover type:

Failover method:

Failover retries:

Failover delay:

Failover restore: NONE

Connection Load Balancing Goal: LONG

Runtime Load Balancing Goal: NONE

TAF policy specification: NONE

Edition:

Pluggable database name:

Hub service:

Maximum lag time: ANY

SQL Translation Profile:

Retention: 86400 seconds

Failback :  true

Replay Initiation Time: 300 seconds

Drain timeout:

Stop option:

Session State Consistency: DYNAMIC

GSM Flags: 0

Service is enabled

Preferred instances: orcl1

Available instances: orcl2

CSS critical: no

Service uses Java: false

[oracle@oel70-base1 ~]$

Note: Please have a look at these properties

1. Session State Consistency: DYNAMIC

2. Failback                            : true

Thanks for looking this feature and blog. Happy learning.