Despite the many benefits of server virtualization, the technology still poses challenges for corporate data centers.
TechTarget's recent "Virtualization Decisions 2009 Purchasing Intentions Survey" asked users to identify their server virtualization challenges, and the list was substantial. Backing up virtual machine data and managing storage are two of the biggest challenges for both VMware and Microsoft shops, according to the results.
VMware server virtualization challenges
Out of 386 VMware users who responded to the question, 36% said I/O bottlenecks are a challenge, 30% named backing up virtual machine (VM) data and 28% listed storage management.
Christian J. Metz, the director of IT at the Orange County United Way in Irvine, Calif., which uses VMware widely in its data center, said data backup and server availability monitoring are his biggest server virtualization challenges.
VMware has a virtualization backup console, but it's a costly add-on -- one that his nonprofit can't afford, he said. The backup console also requires a plug-in tool at an additional cost, he added.
"The functionality that should really be there isn't really there: the ability to back up an entire server," Metz said.
To work around the problem without buying expensive add-ons, the United Way's IT team had to write custom scripts to perform its system backups.
When it comes server availability monitoring and metrics, the issue is that VMware doesn't include a built-in real-time monitoring tool, Metz said. The built-in tool gives only point-in-time data on performance, and third-party tools that would provide greater insight are too expensive for his group to purchase, he said. His team has done some workarounds to improve monitoring, but the process still falls short.
"At this point, we've kind of given up on it, to be honest," he said. Metz used to see I/O bottlenecks until his IT team moved to an iSCSI storage area network architecture from internal disk arrays on Dell servers.
"When we did that, pretty much all of our I/O issues went away," he said.
Microsoft Hyper-V server virtualization challenges
Microsoft Hyper-V users face similar server virtualization challenges, according to the survey data.
Out of 78 respondents, 31% said that backing up VM data is a challenge of virtualization, 29% said they struggle with server availability monitoring and metrics and 21% identified troubles with storage management.
Rob McShinsky, a senior systems engineer at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., said his experiences are consistent with the survey results.
"Backups are my lifeblood," he said. "If I can guarantee that I can get consistent backups, then I feel I can recover if it all goes down."
The problem with that, though, is the same one shared by many VMware users: the available utilities and backup add-on products for Hyper-V are limited.
"They were pretty much nonexistent, so we came up with some scripted backups" by using tools from Windows Server 2003, McShinsky said. "The problem we've seen is that the support from backup vendors is slow."
Because the medical center uses a six-node cluster with 100 guests, standard Windows backup tools don't work for them, he said.
Another problem is that Hyper-V's fixed-disk virtual hard disks must have adequate free space to allow applications to perform well. That means wasted space and extra hassles in configuring systems, McShinsky said.
"I think Hyper-V R2 will help with some of this, with its clustered file system," McShinsky said.
Greg Shields, an independent virtualization and Hyper-V expert, said the overall survey results jibe with the feedback he hears in the field from many virtualization users. No matter which hypervisor you choose, said Shields, it's not uncommon for virtualization to bring new problems to existing IT systems.
"When you add virtualization to an environment, you make things easier, but you also make things much, much more complex," he said.
Todd R. Weiss is an award-winning technology journalist and freelance writer who worked as a staff reporter for Computerworld.com from 2000 to 2008. He spends his spare time working on a book about an unheralded member of the 1957 Milwaukee Braves and watching classic Humphrey Bogart movies. Follow him on Twitter @TechManTalking.