Use case: 

- Suppose we have multiple namespaces and we want to migrate namespace one after another and it will have some dependencies  in your application, so that it needs to be migrated at target side to migrate in sequence. In that case you can just create a level here. Once you start creating level, it will keep adding level here. 


- Control maximum parallel syncs at DR Policy level.

- Control maximum parallel syncs at cluster level.   



For this you have to create a DR Policy. Please check below steps on how we can set up the DRP Ordering level.


1. Go to the DR Policy administration and create a any policy, we support passthrough, stage1 and stage2 as well.

2. After creating a DR Policy, click on that policy and apply with 'Application Replication'.

3. Once you click on apply you will see windows and it will see a 'Order level', by default it will be a 'Level-0'



4.  Then , 'Apply' the Policy and you will see the 'Order level' on the screen.



5. While applying a DR Policy user will be given an optional option to specify the order level for the DR Policy operation, if the order level is not configured for the operation the operation will be added at level-0. DR Policy operations at a specific level will be triggered simultaneously. Levels will execute one after another in ascending order of the level.


6. We have added another Level-1 you can see in the below snippet. Once Level-0 completed then automatically Level-1 will be started. It will run one after another so that SWIFT load will be decrease.



 

7. You cannot set up same configuration for same order level otherwise it will throw an error saying .


Failed to apply DR policy DRP_Ordering.

Detailed Error: The DR policy 'DRP_Ordering' is already applied to the input sync job.

The corresponding DR operation key=6.



8. If you want more information about DRP ordering, you can simply run the mentioned command on the SWIFT server.

#sc drp app --help | grep "order-level"



# Limitation:


  • SWIFT will allow DR Policy ordering for Stage12 policy with stage2 schedule as execute after stage1. For Stage12 policy having stage2 schedule other than execute after stage1, levelled policy won’t be allowed. In future.
  • Modification of level of a  drp operation is not allowed if any operation within the drp operation level is under execution. 
  • There should be at least one drp operation in level-0, all operations from level-0 cannot be moved. 
  • Failover/fallback are prohibited at DR Policy operation level for levelled policy, will be allowed only at policy level. 
  • If multiple operations are added to policy with start execution time (before creation of any other level) the policy will not have levelled structure instead it will behave same as existing DR Policy design. 
  • If DR Policy is levelled then DR Policy apply with start execution time will not be allowed for application for DR Policy operation, if start execution time provided for DR Policy operation then it will error. 
  • Unapplying a specific operation is permitted only when the associated order level is not currently running. 
  • Unapplying the last operation from order level-0 will unapply all operations from subsequent levels and deletion of all order levels associated with the policy. 
  • Unapplying the last operation from order level-0 is allowed only when all order levels are idle. 
  • Unapplying the policy is permitted only when all order levels are idle and will result in deletion of all order levels associated with the policy. 
  • Unapplying the last operation from order level other than level-0 will only unapply the operation and will not delete the order level. 
  • For level employed DR Policy, pausing all operations from an order level will pause all operations from subsequent levels