Ever since the second computer was attached to the first network, interdependency has grown. Servers depend on each other to provide vital services and applications are distributed over machines. Disaster recovery is not just a question of recovering a database, when servers also need name and directory services to find each other again across a network. The trap is to apply disaster recovery to the different IT components in isolation and to define aggressive recovery time objectives that fail to take into account the linkages between the components needed to make the whole system work. Already a puzzle for the IT department, interdependency is a challenge for other parts of the business too.
Handling interdependency in disaster recovery plans means taker a broader view. The whole is greater than the sum of the parts. Not only do IT systems and structures have to be considered globally, but functional dependencies between groups must also be assessed, both inside and outside an organization. The recovery effectiveness (or lack of it) of customers and suppliers can dramatically affect a company, as can outages or non-availability of public services. Recovery industry vendors may be effective and efficient in serving one organisation coping with a business disruption, but how well they serve several disrupted organisations at the same time is another matter.
There’s no miracle solution for handling interdependencies. It’s a matter of systematically listing the different components that are needed to make a complete system (infrastructure, department, business or even community) work and assessing the interactions and inter-reliance. Then step by step the weakest links with the most probability and impact of failing have to be strengthened, notching up each time the organisation’s robustness and capability to keep on running in the face of adversity. For effective disaster recovery, organisations to take into account include other major enterprises, communications, utilities and transport providers, as well as government, public and any other major service suppliers.