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Backup challenges: Backing up virtual servers

In the second part of this primer on backup challenges today, Brien Posey explores why backing up virtual servers creates data protection challenges.

Data growth, the need for more frequent data protection and a variety of other challenges have forced administrators to look for alternatives to traditional backups. The second part of this primer on backup challenges today explains why backing up virtual servers presents challenges for IT pros.

In recent years, backing up virtual servers has been another source of headaches for backup administrators. When server virtualization first gained mainstream acceptance, the backup process had a lot of catching up to do. Most backup applications were not virtualization aware, and backup administrators were only beginning to understand the ways in which virtual environments differed from physical server backups.

Initially, most backup administrators chose to back up virtual machines by deploying backup agents to each individual virtual machine. Ultimately, however, this approach proved to be inefficient at best. As virtual machines proliferated, managing large numbers of backup agents became challenging. Never mind the fact that, at the time, many backup products were licensed on a per-agent basis. Resource contention also became a huge issue since running multiple, parallel virtual machine backups can exert a significant load on a host server and the underlying storage.

Today, all of the major third-party backup vendors offer products that are virtualization aware. These products are generally able to perform host-level backups rather than requiring a separate backup agent for each virtual machine. Although this approach is vastly superior to that of deploying a separate agent onto each virtual machine, host-level backups present challenges of their own.

One such challenge stems from the fact that not all virtual machines are created equally. Some are difficult to protect using host-level backups. As previously mentioned, host-level backups tend to protect individual virtual machines through image backups. This process generally works by creating virtual machine snapshots and then tracking storage block modifications. In order for the process to work properly, however, the virtual machine must be running a supported operating system and the backup application must be compatible with all applications that are running on the virtual machine.

Virtual machine mobility also makes host-level backups challenging. Both VMware and Microsoft offer products that allow a running virtual machine to be moved from one host server to another. This means that when a host-level backup is created, it is entirely possible that the host will be running a completely different set of virtual machines than it was running the last time that a backup was made.

Check out our entire data protection primer on identifying data backup solutions for today's challenges.

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