Host-based vs. agent-based backup – Some pros and cons
No matter how much availability you put in place via virtualization, you still have to back everything up. It's apparent that consolidating servers with a hypervisor adds some options to the mix. Specifically, you need to decide if you want to protect workloads in a traditional way – that is, by installing a backup agent into each virtual machine – or do you want to use a backup tool that can integrate with your hypervisor?
More and more data protection products are becoming hypervisor friendly, making it possible for administrators to more easily implement different protection options against workloads appropriate for that option. For example, Microsoft's Data Protection Manager 2010 can protect both individual servers and virtual machines or it can protect virtual machines running under Hyper-V without requiring that each virtual machine have an agent installed. It depends on whether or not the guest operating system is supported as to whether or not DPM 2010 will allow a level of granularity in the recovery, though. If the guest OS supports VSS, you can recover single items from within DPM.
Perhaps the biggest downside to hypervisor protection in DPM 2010 lies in support for applications such as SharePoint, SQL Server and Exchange. If you want native support for these applications, you need to use guest-based protection with DPM 2010.
Of course, DPM only addresses the Hyper-V side of the equation and there's a whole ton of VMware out there. In these cases, if you want to move beyond protecting at the individual virtual machine level, you'll need some other backup tool such as Veeam Backup & Replication. This tool, and others like it, leverage the unique properties of virtual machines to make backup and recovery a breeze while also enabling additional capability. For example, with Veeam's tool, you can create an on-demand sandbox which allows you to quickly stand up lab environments. Of course, you can perform similar feats using traditional backup and recovery tools, but it certainly takes more effort and is more error prone.
Although some of today's newest backup tools can work miracles when combined with a virtual infrastructure, many IT people have a whole lot of comfort with traditional backup methods and are loathe to jettison those well-worm techniques. And, there's really nothing wrong with that approach as long as data gets protected. That is, after all, the primary goal of a backup system. If, however, you want to add new capability that leverages your virtual infrastructure – which includes your hypervisor and your SAN – you need to consider the use of hypervisor-aware protection tools.