Until the past year or so, backup tools for virtual infrastructure came in two flavors: tools that could back up the data inside a virtual machine (VM), which usually relied on guest agents, and tools that could make a copy of a VM's system image, which usually operated at the host level.
But as users deploy more and more VMs, the cost of a software agent for each VM -- and the complexity of managing them all -- has become prohibitive. And as host-level tools gain the ability to back up system images as well as the data within VMs, most enterprise virtualization pros agree that guest-level agents are on their way out.
"Agent based is not the way to go anymore," said Jason Boche, a virtualization evangelist and a VMware user at a large enterprise.A shift toward agentless technologies
Recent survey data also indicates a shift from guest-level backups. Among 809 respondents to TechTarget's " Virtualization Decisions 2010 Purchasing Intentions Survey," 52.3% said they use host-level backups -- up from 35% in 2009. Meanwhile, the popularity of guest-level backups decreased slightly, from 62.2% to 58.8%.
Agent based is not the way to go anymore.
John Chirhart, a consultant at the defense contractor InfoReliance, said he's seen a similar shift among his clients -- not just in backups, but in other aspects of data center management as well.
"Backup is just one area where we see this trend," he said. "Agentless technology for the virtualization space is being quickly adopted elsewhere, such as antivirus."
Still, moving to host-level backups isn't as simple as flipping a switch.
"You might not have to manage an agent, but there's no free lunch," said Rick Vanover, a virtualization expert at a financial services firm in the Midwest. "It's still a burden to keep [software] up to date. There's a re-architecture, additional skills and thought that go into [host-level backup] too."
Host-level backup products have added these capabilities, but they're still relatively new and require testing before users trust them for data protection. Veeam Software's Backup and Replication 5.0 suite, for example, will be able to perform granular restores of data from within image-level backups, but its release is currently slated for mid-October.
Donald Tedesco, data center supervisor for Swarthmore College Information Technology Services, said he's planning to evaluate the new Veeam release.
If you want to get a good backup of databases ... you need an agent.
VMware administratorMichigan State University
"Their solution is really innovative," he said, but the proof is in the pudding. "I'll be interested how it all works for real."
Some users don't see agents ever disappearing completely.
"If you want to get a good backup of databases or Exchange, you need an agent," said Ed Symanzik, a VMware administrator at Michigan State University. "An agent will also let you restore a single mailbox or database table."
Chirhart predicted that the adoption of host-level backups will mirror the adoption of virtualization itself, beginning with low-hanging fruit and progressing to mission-critical applications such as databases.
"I don't think agents are going to go away anytime soon," he said. "Applications like Exchange and Oracle will be some of the last ones to go."
Beth Pariseau is a senior news writer for SearchServerVirtualization.com. Write to her at firstname.lastname@example.org.