However, it should be taken into account that this process will be time-consuming – to restore the operational readiness of the systems or applications selected in the Business Continuity Plan, it is necessary to build resources from images.
Cloud DR solution vs data backup
Unlike ordinary data backup, Disaster Recovery solutions offer the possibility of almost immediate take over at least part of the workload in the event included in the Business Continuity Plan. At the same time, the DR solution in the cloud is associated with incurring a higher cost - in addition to the data backup itself, it requires additional continuously running cloud resources that are ready to take over the planned load as part of the Disaster Recovery process. At the same time, the larger the scale of continuously running DR solution resources against planned target size of the DR environment, the higher the RTO standard – the speed of restoring technical readiness to continue system and business processes.
There are various strategies for DR solutions in the cloud. These are based on determining the cost level and the intended level of the RTO/RPO standard. At the same time, the relationship between these two levels is in inverse proportion. Based on the BCP/DR plans, it can be determined which DR strategies should apply to the selected systems of the organization. Such mapping assumes the analysis of IT processes and services in terms of their criticality for maintaining business continuity and ensuring security. As a consequence, different Disaster Recovery strategies can be applied to different systems.
Types of DR cloud strategies
The most expensive Disaster Recovery strategy, but at the same time giving the possibility of almost immediate takeover of processes on a full scale, is the 'Multi-site' strategy. It is based on an active/active approach, where the cloud environment operates at scale to match the target workload planned for the DR solution and with close to zero data loss when an event occurs.
On the other extreme side, is the DR strategy with the lowest maintenance costs - the 'Backup & Restore' strategy. This is an 'active/passive' configuration – where the active data center serves as the primary, and the second data center is built as a Disaster Recovery facility, where specific actions are required to prepare it before taking over the target load as part of the DR process.
The compromise of the 'Backup & Restore' strategy is the acceptance of a long time needed to restore the full operability of the solution. Only a minimal part of the services is launched in the cloud and if a DR event occurs, it is necessary to almost completely restore the DR resources required for the DR solution in the cloud, which, despite the automation of the process, translates into a worse RTO. The recovery time depends on the size of scaling, the services selected, the complexity of the restored and scaled infrastructure, the availability of cloud resources, the provisions of the contract with the cloud provider, etc. It can also be assumed that along with the lower cost of the Disaster Recovery solution, the RPO may also deteriorate, forcing the organization to accept greater data loss or pressure to change the strategy or the way data replication is configured.
There are intermediate solutions between these strategies, which are considered as 'active/passive' configuration. The intermediate scenarios are usually implemented to ensure a balance between cost, speed of post-disaster or other incident recovery, and acceptable level of lost data
- 'Pilot Light': only critical system resources are running continuously in the cloud. In the event of a Disaster Recovery event, scaling of resources to the planned level is initiated. It is assumed that scaling for 'Pilot Light' takes several tens of minutes.
- 'Warm Standby': a fully functional environment is running that can take over some processes. However, scaling up to the planned level is still required. In this strategy, you can assume that scaling will be counted in minutes.
Support for Disaster Recovery processes by cloud solutions
Both in the variant of secure data backup in the cloud and the full Disaster Recovery Cloud solution, it is necessary to:
- assess the risk of solutions,
- create a comprehensive architecture taking into account areas of integration, data, applications or services, infrastructure and updates of corporate architecture of the organization,
- develop operational processes necessary to maintain the solution.
In addition to Disaster Recovery solution, an organization may also consider providing employees with operating system virtualization services along with virtual desktops and cloud applications. The above will ensure a secure working environment independent of physical company machines.
The subject of Disaster Recovery in the cloud can take on a diverse scale and catalogue of services used, depending on the needs of the organization. By addressing the subject of DR in the cloud, the organization opens up discussion and action on many aspects of cloud solutions, including, among others:
- construction and configuration of the basic cloud environment (including, inter alia, basic architecture with the necessary services, network settings, settings for identity management, etc.),
- communication channel between the organization's data centers and the cloud platform,
- ensuring regulatory compliance for the use of the cloud solution by the organization,
- testing the Disaster Recovery solution, e.g. switching to the DR solution, verifying the correctness of data backup, etc.