CONSULT CIRCLE | BUSINESS CONTINUITY
A plain-English glossary of the terms that appear in disaster recovery plans, supplier contracts and audit questions.
Disaster recovery has an unusually dense vocabulary, and much of it appears in contracts and audit questionnaires where misunderstanding is expensive. This glossary explains what each term means in practice, and why it matters when you are the one signing.
The two that matter most
| Term | Definition | In practice |
|---|---|---|
| RPO — Recovery Point Objective | The maximum acceptable amount of data loss, expressed as time | An RPO of four hours means you accept losing up to four hours of work. It determines how often data must be copied |
| RTO — Recovery Time Objective | The maximum acceptable time to restore service after an incident | An RTO of two hours means being operational within two hours of declaring. It drives most of the cost |
Table 1 — RPO and RTO.
Set both per system: A single organisation-wide figure either overspends on systems that do not need it or under-protects those that do. Different systems warrant different answers.
Planning and governance terms
| Term | What it means |
|---|---|
| Business Continuity Plan (BCP) | How the organisation keeps operating during disruption, covering people, premises and processes as well as technology |
| Disaster Recovery Plan (DRP) | The technology component: how systems and data are recovered. A subset of business continuity |
| Business Impact Analysis (BIA) | The assessment that establishes what each process is worth and how long it can be unavailable. It is what RPO and RTO should be derived from |
| Maximum Tolerable Downtime (MTD) | The point beyond which disruption causes unacceptable or unrecoverable damage. RTO must sit comfortably below it |
| Recovery Consistency Objective (RCO) | How consistent recovered data must be across interdependent systems. Relevant where systems must agree with one another |
| Crisis management | Decision-making and communication during an incident, including who declares and who speaks externally |
Table 2 — Planning and governance terms.
Technical terms
| Term | What it means |
|---|---|
| Failover | Switching operation from primary to a secondary environment |
| Failback | Returning to primary once it is restored. Frequently harder than failover and routinely under-planned |
| Replication | Continuously copying data or systems to a secondary location. Synchronous replication confirms writes at both ends; asynchronous allows a lag |
| Hot, warm and cold site | A hot site is running and ready; a warm site has infrastructure needing activation; a cold site is space and power with no equipment ready |
| Pilot light | A minimal always-on version of the environment that can be scaled up quickly when needed |
| Immutable backup | A copy that cannot be altered or deleted for a retention period, even by an administrator |
| Air gap | A copy isolated from the network so it cannot be reached by an attacker who compromises production |
| 3-2-1 rule | Three copies of data, on two media types, with one offsite. A widely used minimum standard |
| Runbook | The step-by-step recovery procedure, written to be followed under pressure by someone who did not write it |
| Orchestration | Automating recovery steps and their sequence, reducing both recovery time and human error |
Table 3 — Technical terms.
Service and contractual terms
| Term | What it means | What to check |
|---|---|---|
| DRaaS | Disaster Recovery as a Service. A provider maintains a standby environment ready to run | Whether RPO and RTO are contractually committed or merely described |
| Declaration | The formal act of invoking disaster recovery | Who is authorised, how it is done, and the provider response time |
| SLA | The contractual service commitment | What is actually guaranteed, and what the remedy is if it is missed |
| Invocation cost | Charges arising when the service is actually used | Whether resources during an incident are included or billed separately |
| Test window | The agreed period for testing recovery | Frequency, whether it is disruptive, and whether it is included |
| Shared responsibility | The division of duties between you and the provider | Everything not explicitly the provider’s is yours, including most data protection |
Table 4 — Service and contractual terms.
The term that causes most disputes: Shared responsibility. Cloud and service providers protect their platform. Your data, your configuration and your access controls generally remain yours. A great many organisations discover this distinction during an incident rather than before one.
Related reading
- DRaaS vs traditional backup: choosing the right business continuity plan
- Backup and disaster recovery for SMBs: requirements, tests and cost traps
- BC/DR Planning and Disaster Recovery Services
Frequently asked questions
What is the difference between RPO and RTO?
RPO is how much data you can afford to lose, measured in time. RTO is how long you can afford to be down. RPO drives how often data is copied; RTO drives the recovery method and most of the cost.
What is the difference between business continuity and disaster recovery?
Business continuity covers keeping the organisation operating, including people, premises and processes. Disaster recovery is the technology component within it. A disaster recovery plan without a business continuity plan restores systems into an organisation that may not be able to use them.
What is the 3-2-1 backup rule?
Three copies of your data, stored on two different media types, with one copy offsite. It is a widely used minimum standard, increasingly extended to include an immutable or air-gapped copy.
What is a pilot light environment?
A minimal always-on version of your environment holding core components, which can be scaled up quickly when needed. It costs less than a hot site while offering faster recovery than starting from nothing.
Why is failback often harder than failover?
Failover is planned and rehearsed because it is the emergency. Failback involves synchronising data changed while running on the secondary environment, often with the business live on it. It is frequently treated as an afterthought and should not be.
Talk to Consult Circle
We help organisations translate these terms into a plan that has been tested rather than written, with RPO and RTO derived from business impact.
Book a free 30-minute call - 0203 916 5593 - info@consultcircle.com