Offsite copies, and the egress bill

A second copy in a second provider, and a bill that arrived a month later showing the transfer cost more than the storage.

monthly, 400 GB of backups:

  storage, provider A          £4.60
  storage, provider B          £5.20
  egress A → B, full copies   £31.00
  ─────────────────────────────────
                              £40.80

after switching to incremental with a monthly full:
  egress                       £6.40
  total                       £16.20

Egress pricing makes a naive offsite copy cost several times the storage, and the fix is the same one that has always applied to backups — incrementals with periodic fulls. The number to keep an eye on afterwards is restore time, which goes up with the chain length, and the drill is what turns that from a theory into a measured figure.