#33 Hybrid Cloud: Three (3) DR Models
Choosing the DR solution model.
At a high level three different models can guide your DR thinking. Each idea being associated to different performance criteria such as time to restart after an incident and maximum data loss allowed that may occur from an incident.
Key concepts are 1. RTO - recovery time objective and 2. RPO - recovery point objective
- Active|Active: this type of solution implies the use of active components on multiple sites, involving both running the production workload and active data replication required to maintain a copy of what is running in the other site. The primary and secondary data centers must have low network latency to avoid performance impacts. These solutions usually require the IT resources in the second data center to always be in use. This has cost implications.
2. Active|Passive: in this type of solution the only active components in the DR site are those required to sustain the data replication process. All the other components are provisioned on-demand.
3. Passive only: the required components in the DR site, including data, are provisioned on-demand and the data can be obtained / re-loaded from a back-up copy
In case there is a disaster, the DR solution must meet the following requirements:
- Ability to access DR configuration information within the time frame that has been agreed upon with the cloud provider.
2. Access to a data center site with availability requirements and metrics consistent with the source site.
3. Ability to restart operations in full compliance with expectations according to the agreed upon RTO and RPO.