overlay-nami/scripts/disk_layout.json

{
  "_comment": "See http://www.chromium.org/chromium-os/building-chromium-os/disk-layout-format",
  "parent": "../../baseboard-nami/scripts/disk_layout.json",
  "layouts": {
    "common": [
      {
        # 4GB stateful partition to store temporary files during testing.
        "num": 1,
        "size": "4 GiB"
      }
    ]
  }
}