Migrate

Phases allowed: warm, cold.

Moves the index to the data tier that corresponds to the current phase by updating the index.routing.allocation.include._tier_preference index setting. ILM automatically injects the migrate action in the warm and cold phases if no allocation options are specified with the allocate action. If you specify an allocate action that only modifies the number of index replicas, ILM reduces the number of replicas before migrating the index. To prevent automatic migration without specifying allocation options, you can explicitly include the migrate action and set the enabled option to false.

If the cold phase defines a searchable snapshot action the migrate action will not be injected automatically in the cold phase because the managed index will be mounted directly on the target tier using the same _tier_preference infrastructure the migrate actions configures.

In the warm phase, the migrate action sets index.routing.allocation.include._tier_preference to data_warm,data_hot. This moves the index to nodes in the warm tier. If there are no nodes in the warm tier, it falls back to the hot tier.

In the cold phase, the migrate action sets index.routing.allocation.include._tier_preference to data_cold,data_warm,data_hot. This moves the index to nodes in the cold tier. If there are no nodes in the cold tier, it falls back to the warm tier, or the hot tier if there are no warm nodes available.

The migrate action is not allowed in the frozen phase. The frozen phase directly mounts the searchable snapshot using a index.routing.allocation.include._tier_preference of data_frozen. This moves the index to nodes in the frozen tier.

The migrate action is not allowed in the hot phase. The initial index allocation is performed automatically, and can be configured manually or via index templates.

PUT _ilm/policy/my_policy
{
  "policy": {
    "phases": {
      "warm": {
        "actions": {
          "migrate" : {
          },
          "allocate": {
            "number_of_replicas": 1
          }
        }
      }
    }
  }
}

PUT _ilm/policy/my_policy
{
  "policy": {
    "phases": {
      "warm": {
        "actions": {
          "migrate" : {
           "enabled": false
          },
          "allocate": {
            "include" : {
              "rack_id": "one,two"
            }
          }
        }
      }
    }
  }
}