Move a shard manually (reroute)

Command

POST /_cluster/reroute
{
  "commands": [
    {
      "move": {
        "index": "customer",
        "shard": 0,
        "from_node": "node-1",
        "to_node": "node-2"
      }
    }
  ]
}

What it does

Manually moves a specific shard from one node to another.

When to use it

To fix an unbalanced shard distribution or to drain a specific node.

Caution

It can conflict with automatic rebalancing; moving large shards creates network and IO load.