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The economics of DR
Server virtualization is typically equated with running multiple virtual machines on a single physical server for improved resource utilization and hardware consolidation. Improved business continuity and lower data center operating costs are additional, compelling benefits that are fast becoming the primary drivers of server virtualization deployments. Today, the closest IT organizations can come to guaranteeing a service level for a specific application in a physical server environment is to deploy infrastructure and applications as dedicated silos that are isolated from any potential outside impact. However, this type of implementation leads to poor utilization and the likely purchase of additional hardware for high availability. But server virtualization can enable the sort of business resilience you need without the compromises that come with silos. When talking server virtualization and business continuity, there are a few key concepts to understand.
- Hardware independence.
Server virtualization provides a layer between the physical hardware and the operating system and applications, allowing virtual machines to run on any approved x86 hardware.
- Isolation.
Multiple virtual machines run in an isolated environment, independent from one another. If one virtual machine goes down, it doesn't affect others running on the same host. Because multiple operating systems can be run on one physical machine, hardware utilization is improved. This creates a cost-effective means of establishing failover targets in DR strategies.
- Encapsulation.
Virtual machines are stored as hardware-independent files. Encapsulating the virtual machine into a single file enables mobility and allows multiple copies of the virtual machine to be created for DR purposes.
Marrying server virtualization with the business continuity solutions employed in physical environments--such as replication--enables a more cost-effective DR strategy. Replication provides a mirror copy of primary system data on a local or remote secondary system. If the primary system has an interruption of service, the secondary system can take over, minimizing downtime and data loss.
In a physical-to-virtual (P2V) configuration, a production application running on a physical machine is replicated to a virtual machine running on a secondary system. A virtual-to-virtual (V2V) scenario has production and recovery applications running on virtual machines. By periodically or continuously replicating over a LAN or WAN to a virtualized standby system, a higher degree of synchronization is achieved. With greater frequency of replication, data loss is minimized in the event of an outage.
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