autorestic/docs/pages/location/options/copy.md

Copy

Instead of specifying multiple to backends for a given location you can also use the copy option. Instead of recalculating the backup multiple times, you can copy the freshly copied snapshot from one backend to the other, avoiding recomputation.

Example

locations:
  my-location:
    from: /data
    to:
      - a #Fast
      - b #Fast
      - c #Slow

Becomes

locations:
  my-location:
    from: /data
    to:
      - a
      - b
    copy:
      a:
        - c

Instead of backing up to each backend separately, you can choose that the snapshot created to a will be copied over to c, avoiding heavy computation on c.