What is Disaster Recovery?

Disaster Recovery (DR) encompasses the procedures, policies, or processes that prepare an organization's vital IT infrastructure to recover effectively from natural, man-made disasters or cyber attacks, and to ensure business continuity. The DR must cover any possible scenario that threatens the availability of the IT infrastructure.
In recent years, DR has taken on an increasingly predominant role in companies' budgets, often accounting for 20-25% of IT spending.

The correct Plan

A DR plan outlines how an organization will respond to any disaster scenario, in order to support time-sensitive business processes and functions and maintain business continuity.
This plan contains both receptive and preventive elements and is a key part of the company. On the receptive side, the plan outlines numerous disaster scenarios and defines the detailed responses to each, in order to reduce the negative impact of the event. In terms of prevention, the plan minimizes the negative effects of specific scenarios, defining what the organization must do to avoid them.
Specifically, a plan must anticipate and delineate an action plan in response to the loss of such critical IT components and services, such as:

• Complete critical hardware environments
• IT hardware, including network infrastructure, servers, desktop or laptop computers, wireless devices and peripherals
• Service provider connectivity
• Enterprise software applications
• Data storage devices or applications

To achieve maximum efficiency and keep costs under control, organizations should use a combination of internal resources and solutions provided by vendors in their disaster recovery planning. The optimal internal / provider mix depends on the specific disaster recovery objectives of the organization, which are measured by the Recovery Time Objective (RTO) and the Recovery Point Objective (RPO). The recovery time objective can be defined as the period of time in which a business can operate without system availability, while the recovery point objective expresses how old the data will be once the systems recover.

Disaster Recovery in Data Center

To meet an organization's RTO and RPO goals, data center operators face a key challenge: data synchronization. In other words: How to ensure that data from all alternative locations is up-to-date to ensure service consistency and business continuity, even in the event of a disaster?
To some extent, the answer to this question is the level of replication, which can be defined as the frequency with which the receiving system (backup environment) recognizes the receipt of data from the sending system (production environment). The most common replication methods are:

When creating a Disaster Recovery Plan, organizations must ensure that their recovery policy is complementary to the chosen timing method.
For example, the "hot" synchronization / recovery policy ensures that data is always 100% synchronized and that a parallel system is always ready to take over the production system with minimal latency or downtime. However, if a data center has chosen asynchronous replication, the cost of maintaining a "hot" server may not be justified, as the data may not be fully replicated at some point in the failure.