3. Difficulty managing shared storage
Some 23 percent of the administrators we polled reported that server virtualization creates new headaches in managing shared storage.
Enterprises typically have a lot of different workloads being stored on storage systems, and for administrators, there aren't always clear connections among the storage volumes, the workloads that each volume supports, the demands against each volume, and who is consuming capacity.
"Essentially, the virtual infrastructure has created another layer of abstraction on top of the storage infrastructure without really freeing you from the complexity of the physical layer," Boles explains. "Now you have this virtual storage layer that you're managing, made up of [VMware's] VMFS, all the different virtual server files and data, and you're provisioning those resources inside the virtual infrastructure -- maybe even executing operations like snapshot." On top of all that, "you still have to take care of the physical infrastructure and look at I/O demand. Having those two layers makes it harder to connect the dots between them," he says.
How to deal: Consider thin provisioning, a storage virtualization capability that helps curb low storage utilization by allocating data to free space. Physical storage is allocated on demand from a shared pool, but only when needed. By using thin provisioning along with server virtualization, users can optimize both server and storage utilization rates. Virtualization appliances and arrays from vendors like 3Par, Compellent, DataCore Software, and NetAppl include thin provisioning functionality.
4. The need to adapt the storage infrastructure to serve both physical and virtual environments
In a finding that's similar to the backup and recovery dilemma, 20 percent of the polled administrators said that they find it hard to adapt their storage infrastructure to handle a mix of traditional and virtual processes.
How to deal: When jumping into virtualization solutions that will mingle with physical environments, "make sure you're doing it with the best storage vendor you can find for ease of use, simplicity and virtual infrastructure integration," Boles says.
Some of the big vendors' offerings are integrated with the virtual infrastructure, reducing the complexity of these systems "so you don't have to do a lot crazy stuff, such as disk group configuration," he adds. "You want one-click setup of storage and [access to] fine-grain granularity provision storage so you can carve up resources, understanding who's using what, and manage it over time."
Some large-scale IT departments are even making a complete switch to technologies like an NFS-NAS setup, which is ready to go into production underneath a virtual infrastructure. "You can store a whole bunch of virtual machines on one storage mount point and not have a lot of complexity around that," says Boles. "There aren't nearly as many headaches as trying to coordinate some of those physical storage resources with a very virtual server infrastructure."
5. Trouble choosing the right kind of networked storage for virtualized servers
Some 18 percent of the storage professionals surveyed said that they can't decide on the right kind of networked storage for virtualized servers. "The right kind of networked storage makes a difference -- because you can scale, and get better performance and more simplicity in your processes [if you choose correctly]," Boles says. But the right solution depends largely on the organization's objectives.
At Purdue University's Krannert School of Management, for instance, the IT department's top priority wasn't 24/7 availability for its virtualized environment, but rather fast recovery time when -- not if -- the system went down, says IT manager Jeff Ellow.