Glossary

Cold site

A cold site is a recovery facility with space, power, cooling and network connections but no servers, storage or data. It is the cheapest disaster recovery option to maintain, and its real recovery time is the time to obtain and install hardware plus the time to restore data onto it.

The stages of a cold-site recovery

  1. Activate the site contract and gain physical access.
  2. Obtain hardware, through new orders or a pre-arranged supplier commitment.
  3. Ship, rack, power and cable the equipment.
  4. Install operating systems and configure storage and networking.
  5. Restore data from backups held somewhere that survived the event.
  6. Test applications and move users across.

Each stage waits for the one before it, so delays add up rather than overlap.

The quoted recovery time is usually the wrong one

A cold-site contract can often be activated within hours, and that figure is easily mistaken for the recovery time. An empty room recovers nothing. Enterprise servers and storage commonly take weeks to arrive, and the clock starts only when the order is placed after the event. Data then has to arrive too: 100 TB over a 10 Gb/s link takes about 22 hours at full line speed, and real transfers are slower, as restore throughput explains. The real figure is lead time plus restore time.

Where a cold site fits

For secondary systems that can be down for weeks without serious harm, a cold site is a rational choice because it costs little between disasters. For anything that cannot, it is not a plan on its own, and a warm or hot site covers it instead. The business impact analysis shows which systems fall where. NIST's SP 800-34 lists the cold site as the most basic alternate-site type, with no system equipment installed.

Shortening the wait

Two steps cut most of the delay. A supplier agreement with committed delivery times, or equipment held in reserve, removes the open-ended procurement step. Keeping a copy of the backups at or near the cold site turns a long network restore into a local one. Both cost money between disasters, and adding enough of them gradually turns a cold site into a warm one.