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
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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.
This was first published in June 2007