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More on the challenges of physical and virtual backups

Today’s feature by our Server Virtualization Advisory Board focuses on the backup management challenges in mixed physical-and-virtual infrastructures.

Board member Jack Kaiser let his colleague Randy Weis, a senior solutions architect at GreenPages Technology Solutions, submit a response, and it was so in-depth that we decided to post it as a separate blog entry instead:

How challenging is it to manage physical and virtual backups together?

Physical and virtual server backup strategies can be very challenging, depending on the organization’s size and IT resources.

IT staffers at large companies are very experienced in running and configuring complex backup products that have deep application and OS integration. Small companies have tended to rely on simpler solutions such as Symantec Backup Exec, which still have good Windows application integration and are able to back up to tape. When virtualization began to pick up, physical server data-protection strategies changed emphasis from tape to disk, and from agent-based to snapshot-based.

Several factors can complicate the process, or simplify it. Physical servers are agent-based backups, for the most part. (Snapshot-based approaches for SAN-attached servers are still not nearly as common as the agent-based method.) The agent-based approach doesn’t work nearly as well for virtual servers, since multiple virtual servers are constrained by the I/O limitations of a single physical host. Also, the CPU and RAM burden that a backup agent has is multiplied by the number of VMs.

So other methods, based on snapshots and integration with the VMware service console and management server, have began to gain in popularity for virtual infrastructures. This brings up the basic issues with mixing traditional physical server data protection methods with virtual server backups.

One big difference between virtualization-centric backup solutions and market-leading backup software suites lies in device management and backup tracking. Backup software developed specifically around virtual servers doesn’t have the tape device and advanced catalog management that software such as NetBackup, CommVault or Networker are known for. Virtualization-centric software products that have been recently developed are disk-to-disk solutions that do image or snapshot backups.

The traditional backup software vendors enjoy the advantage of deep OS and application integration — as well as suites of associated storage management products — that newer virtualization-centric methods can’t match. Yet the newer methods have some advantages, such as quicker responses to rapidly evolving virtualization technologies. End users don’t want to have multiple products and methods to have to manage and run, but they sometimes have to employ them in order to meet application and data protection requirements in mixed environments.

In summary, physical and virtual server data protection strategies present challenges in managing backup targets. They differ in their ability to quickly backup and restore at the OS, file and application levels. They differ in refresh cycles and in associated archiving and other storage management capabilities. And they require different levels of integration and different management approaches to the storage and networking systems. These differences and challenges are beginning to converge and be mitigated, but still present challenges to large and small IT shops alike.

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