Swap the roles of DC2 and DC3 in a 2-region, 3-DC cluster

Using FoundationDB
1

We have a pre-prod fdb cluster built upon Kubernetes clusters, consisting of 2 regions and 3 DCs. Region1 = {dc1, dc2} and Region2 = {dc3}. DC1 and DC3 are full sized (98 pods each), while dc2 only has 15 Tx nodes.

Now the Kubernetes cluster at dc3 is tight with computing resources. We want to reduce resource usage of the FDB at dc3. One way to do it is to swap the roles of dc2 and dc3 to shift high resource usage from dc3 to dc2.

We came up with the following plan, and need some help to verify it, as we haven’t done this before.

0. Our current region config:

 { "regions": [
    { "datacenters": [ { "id": "dc1", "priority": 2 }
                       { "id": "dc2", "priority": 0, "satellite": 1 } ],
      "satellite_redundancy_mode": "one_satellite_double" },
    { "datacenters": [ { "id": "dc3", "priority": 1 } ] }
  ]
}

usable_regions=2

1. Take dc2 out of the cluster, by applying this new json:

 { "regions": [
    { "datacenters": [ { "id": "dc1", "priority": 2 } ],
    { "datacenters": [ { "id": "dc3", "priority": 1 } ] }
  ]
}

2. build up dc2 to full capacity as dc3 (from current 15 to 98 pods).

3. exclude dc3, by applying this config:

 { "regions":[
    { "datacenters": [ { "id": "dc1", "priority": 2 } ] }
  ]
}

4. Change regions config to make dc2 as the second region, by applying this config (dc3 not in the config):

 { "regions": [
    { "datacenters": [ { "id": "dc1", "priority": 2 } ],
    { "datacenters": [ { "id": "dc2", "priority": 1 } ] }
  ]
}

5. Wait for the full replication dc1 to dc2 to complete.
We haven’t changed usable_regions. It’s still 2.

6. scale down dc3 to 15 tx pods only.

7. reconfig dc3 as satellite.

{ "regions": [
    { "datacenters": [ { "id": "dc1", "priority": 2 }
                       { "id": "dc3", "priority": 0, "satellite": 1 } ],
      "satellite_redundancy_mode": "one_satellite_double" },
    { "datacenters": [ { "id": "dc2", "priority": 1 } ] }
  ]
}

Can you please help verify that the above steps are feasible and advise any changes needed?

Thank you.
Leo