Relocating Service in Oracle RAC Database

Relocating Services in Oracle RAC is mainly used for maintenance purpose.

Maintenance purpose :- When for Patching(OS/Oracle), we wanted to do it in a rolling fashion, one node at a time as we don't have downtime for the application, we have to relocate service temporarily to other nodes of the cluster.

We can also permanently move a service from one node to another node. We will show both the methods in this article 

Temporary relocation of a Service in Oracle :-

==>srvctl config service -d AMIT -s app_prod
Service name: app_prod
Service is enabled
Server pool: amit_app_prd
Cardinality: 1
Disconnect: false
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Failover type: SESSION
Failover method: BASIC
TAF failover retries: 0
TAF failover delay: 0
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: NONE
Edition:
Preferred instances: AMIT1
Available instances: AMIT2

==>srvctl status service -d AMIT
Service app_prod is running on instance(s) AMIT1

We can see from above that app_prod service is running on AMIT1 instance , now we wanted to do patching on AMIT1 instance.

We will relocate service temporarily to AMIT2 instance and once our maintenance work is done we will relocate it back. 

Relocating a service will not modify the preferred instance and available instance details for a service . This is a temporary job.

We can relocate service temporarily using below methods :-

Using Database instance :-

==>srvctl relocate service -d AMIT -s app_prod -i p1end1 -t p1end2

Using Node details :-

==>srvctl relocate service -d AMIT -s app_prod -c NODE1 -n NODE2

If you want to disconnect all session while relocating the service , we can use -f clause.

Now check the configuration of the service , it's the same :-

==>srvctl config service -d AMIT -s app_prod
Service name: app_prod
.......
TAF policy specification: NONE
Edition:
Preferred instances: AMIT1
Available instances: AMIT2

Once maintenance job is done, relocate it as it was before using same command.

Permanent relocation of a service :-

When we have to permanently relocate a service then we have to modify the config parameters for the service , in this case the preferred instance and available instance details will be changed.

==>srvctl config service -d AMIT -s app_prod
Service name: app_prod
Service is enabled
Server pool: amit_app_prd
Cardinality: 1
Disconnect: false
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Failover type: SESSION
Failover method: BASIC
TAF failover retries: 0
TAF failover delay: 0
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: NONE
Edition:
Preferred instances: AMIT1
Available instances: AMIT2

Now modify the service for preferred instance as AMIT2

=> srvctl modify service -d AMIT -s app_prod -i AMIT2 -a AMIT1

if multiple instances then we can use comma(,)

=>  srvctl modify service -d AMIT -s app_prod -i AMIT2,AMIT3 -a AMIT1,AMIT4

we can use -f to disconnect all active session in the relocation process.

Let's see if configuration modified or not :-

==>srvctl config service -d AMIT -s app_prod
Service name: app_prod
..................
Edition:
Preferred instances: AMIT2
Available instances: AMIT1

It's modified permanently

I hope this article helped you

Thanks

Amit Rath