As virtualization technology garners greater attention in disaster recovery plans, data center professionals must understand the differences between physical and virtual data migrations and all of the implications that are involved with each instance.
With a physical-to-virtual (P2V) approach, physical servers or storage volumes at the primary site are replicated to virtual machines (VMs) or virtual storage volumes at the disaster recovery site. This includes the migration of OSes, applications and data.
P2V is most often used in organizations that want to reduce the server or storage system count at the secondary site because it allows complete replication of the primary environment onto radically different hardware. However, restoring VMs or storage volumes back to physical counterparts can be problematic if any hardware changes take place at the primary site.
The most flexible approach to data migration is virtual-to-virtual (V2V). This enables VMs and storage volumes to be replicated between (and within) the primary data center and DR site, regardless of the underlying physical hardware. V2V DR supports OSes, applications and data. Recovery is simplified in V2V because it's not necessary to meet specific hardware requirements. Tools like VMware Inc.'s VMotion can automate the process.
In a virtual-to-physical (V2P) environment, the OS, applications and data of a VM or storage volume are migrated to a physical counterpart at the DR site. V2P may appear in any number of backup scenarios, such as restoring a tape backup or virtual entity to a physical server or disk array. As with the P2V approach, it may be difficult to run the virtual workload on the physical machine unless that physical server or storage system meets minimum hardware and configuration requirements.
Stephen J. Bigelow, Senior Technology Writer, can be contacted at firstname.lastname@example.org.
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