Published: 12 Jun 2007
Virtualization and power/cooling issues dominated the discussions at Storage Networking World (SNW) in April, which was surprising as neither of these topics has bothered storage pros too much until recently.
Of the 144 presentations at the show, at least a third mentioned virtualization, in particular VMware. The impact of VMware on storage, and interoperability issues associated with virtual machine (VM) technology, was top of mind for many storage pros.
With the flexibility to run VMs anywhere in a grid of servers, organizations are realizing that storage can't be captive to any one server within that grid. Because of the way Fibre Channel (FC) SAN security works by zoning at the physical port level, all VMs on a single physical server have to be in the same zone, which opens up security concerns and contradicts SAN best practices. Several users at the show said they'd implemented masking within the server itself for each VM, by way of the hypervisor's file system, but it was a manual and cumbersome process.
"There are workarounds, and technology such as N_Port [ID] Virtualization on HBAs [host bus adapters] and switches is getting there, but the best practices are still working their way into the system," says Brian Babineau, senior analyst at the Milford, MA-based Enterprise Strategy Group, during a presentation on the impact of VMware on storage networking.
Instead of buying FC SANs, Praveen Asthana, Dell's director of enterprise storage, advocated iSCSI to avoid some of the complexities of connecting storage to virtual servers. "Our call volumes around storage have shot up," says Asthana. The company discovered calls were related mainly to connecting FC storage to VMware. iSCSI SANs, claims Asthana, are much more flexible and cheaper than FC.
Buying iSCSI supports Dell's marketing push, but there's some merit to it because VMs have their own IP address. In IP networking, most of the access control is built around IP addresses, so a VM can find its storage more easily as long as the virtual LANS (VLANs) aren't too restrictive.
"There are some design considerations in a fabric that you have to think about when moving to virtual machines; your server is no longer bound to a physical entity for security or addressing, and you have to be prepared for that," says Asthana.
While a lot of the focus appeared to be on managing storage in a virtual server environment, there were also discussions about the advantages of virtualizing storage. Gary Berger, VP of technology solutions at Banc of America Securities Prime Brokerage, gave a presentation on his company's move to SAN from silos of DAS and overprovisioning hell. The firm deployed 3PAR's storage and thin-provisioning software, which cut storage administration costs by 95% and storage capacity requirements by 50%, and dramatically improved the company's utilization rates, claims Berger.
Some users are even considering their second generation of storage virtualization, courtesy of Sun's recent decision to terminate its 6920 virtualization product. A large western municipality, which preferred not to be named, found the 6920 easy to install and allocate, but was forced to look elsewhere due to support issues. As a result, the company is switching to Hitachi Data Systems' TagmaStore.
But other attendees who had implemented a storage virtualization product were few and far between. Most users said they weren't deploying it because of cost concerns and a fear of putting all of their eggs into one basket.
John McArthur, president and co-founder of Walden Technology Partners, heard an interesting perspective from users on the benefits of virtualization to reduce floor space, power and cooling. "There was less concern about buying too much storage and more about the cost of maintaining, provisioning and cooling it," he says.
A storage administrator at Boeing says his company is looking closely at how much power its EMC Clariion and Centera systems draw as the company builds out a new data center in Denver. "We have a power budget and this has to be part of our evaluation criteria now," he says. Still, Arun Taneja, founder and consulting analyst at Taneja Group, Hopkinton, MA, cautions users that most announcements around "green storage" are "garbage." Vendors are trying to "ride the green curve," says Taneja, by putting green storage on their data sheets. "But they're going to get a bloody nose," he says. "This is a genuine problem that will not be solved by marketing hype."