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As VMware VCB fades, high hopes for better backups

Application programming interfaces in VMware vSphere 4 promise better backup performance and easier management.

Among VMware's customers, there's no love lost for VMware Consolidated Backup (VCB), a backup framework that was introduced with Virtual Infrastructure 3 (VI3). As a result, many users are anxious to move on with backup software that writes to vSphere 4's new vStorage application programming interfaces (APIs).

Compared with the VCB solution, backup software that writes to the vStorage Virtual Disk Development Kit (VDDK) promises faster backup times, better scalability, and easier installation and maintenance, experts said.

"VCB wasn't VMware's finest work, and they know that," said Matt Theurer, the vice president of professional services at Virtustream, a VMware-authorized consultant in Bethesda, Md.

VCB faults and foibles
VCB is a separate application that runs on a separate server, away from the ESX host. As such, it alleviates the performance problems of traditional backup software because it doesn't require putting agents in the VMs and offloads the backup processes onto a proxy server.

On the other hand, VCB "is a bear to maintain," Theurer said. And the fact that it runs on a dedicated Windows server is highly ironic, given VMware's virtualize-everything mantra.

"It's kind of embarrassing," Theurer said. "You go to a customer and tell them to virtualize SQL Server and Exchange, but, 'Oh by the way, you need a dedicated Windows box for backup; it kind of detracts from the message.'"p>

And VCB performance isn't all that good, said Tom Becchetti, a Unix and storage engineer who backs up a 30-host VMware farm using VCB and Symantec Corp.'s NetBackup. To work, VCB makes a complete copy of the VM before making the backup onto the proxy, which consumes disk space and network bandwidth. All in all, "it's a kludge," Becchetti said.

Support is also a point of contention with VCB, according to Doug Hazelman, the director of global systems engineering at backup software vendor Veeam Software. VCB is a VMware product, but is usually configured alongside a third-party backup package. "If there's an issue, is it VMware's role or the backup vendor's to support it?" he asked. In practice, "customers get bumped around between VMware and the vendor, and they get very frustrated."

Moving to vStorage APIs
While VCB has advantages over the traditional agent-based backup, VMware has moved on and is pushing backup vendors to write to the new improved vStorage APIs in vSphere 4.

So far, several backup vendors have taken the bait: Veeam, Vizioncore Inc. and, most recently, Symantec, which announced the general availability of NetBackup 7 and BackupExec 2010, both of which include support for vStorage APIs. By writing to vStorage APIs, customers no longer have to deploy a separate VCB proxy, simplifying implementation and improving reliability.

But taking advantage of some of vStorage's best features requires customers to run vSphere 4 and to upgrade to the latest version of their backup software. That's not always an option, said Virtustream's Theurer.

"I look forward to the day when I can rip VCB out entirely," he said, "but I have clients that are on backup software that's three versions out."

But for some vSphere shops, upgrading to vStorage-compliant backup software has been worthwhile.

Joe Gremillion, a virtualization and storage manager at the Dallas County Community College District (DCCCD), replaced an older version of Symantec Backup Exec with Veeam Backup 4 in September. He said his backups are completing much faster.

"Basically, the problem with Backup Exec was putting the agents in all the VMs. The backup window was from 6 p.m. to 6 a.m., and it would just kill the infrastructure," he said. In fact, nightly backups weren't even completing. "The only time I would get a complete backup was on the weekends," Gremillion said. With Veeam Backup 4, DCCCD's backups complete every night, he said.

Veeam says the improved performance in Veeam Backup 4 can be attributed to support for changed-block tracking in vSphere 4. With changed-block tracking, vSphere keeps tabs on disk writes, and reports on which blocks have changed since the last snapshot was taken. Without that feature, backup software has to calculate the changed blocks itself to perform an incremental backup.

But backup software that complies with vStorage isn't the be-all and end-all either. For example, Becchetti wishes his firm had implemented VMware Site Recovery Manager (SRM) to perform backup and remote site replication in one fell swoop. "That would have been much more elegant," he said.

Backup once, recover anywhere 
While there's undeniable movement away from agent-based backup in virtual machines, people are expanding their view of backup to encompass data protection as a whole, whether that means recovering an individual file or mailbox message, to replicating entire hosts at an disaster recovery site, said Chris Wolf, a senior analyst at the Burton Group.

In the past, IT departments used to perform specific backups for every conceivable recovery need. But "now the idea is to back up once and recover only what you need," Wolf said. Among the vendors working on that idea are Symantec, CommVault, Syncsort and Vizioncore, he said.

That vision is consistent with the desire of large enterprises for a single data recovery interface, Wolf said. "It shouldn't matter whether the data is in logical partition, a VM or a snapshot on an array . My help desk shouldn't have to know where the backup is in order to recover the file."

Let us know what you think about the story; email Alex Barrett, News Director at, or follow @aebarrett on twitter.

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