The virtual answer

Multivendor provisioning grows easier with new storage virtualization wares.

Storage virtualization isn't a new concept, but it's getting a lot of attention lately as the top storage vendors launch next-generation virtualization wares. The vendors vary on their approaches - some put virtualization in the network, while others put it at the edge or in the array - but they all attack the same basic problem: simplifying storage management.

In traditional storage setups, the intelligence necessary to perform key storage functions such as snapshot copying, data replication and disk mirroring are handled primarily at the host or server level. Implementing virtualization, in which servers view all enterprise storage devices as one large pool of storage, means adding the software, device drivers and so on to each individual server - a situation that is notoriously tough to manage.

The first attempt to move the intelligence necessary for storage virtualization into the network came in 2000-2001 with appliances such as DataCore's SANsymphony and FalconStor's IPstor. These appliances let users pool storage while eliminating the need for drivers and licenses for each server. But this approach never really caught on, primarily because the main Tier 1 storage vendors didn't play along. "We looked at FalconStor's IPstor appliance when we put in our SAN a while back," says Bo Christiansen, IT consultant at SDC Udvikling, a Copenhagen, Denmark, financial firm. "It raised the possibility to integrate the different storage technologies under one GUI, which we liked. But there were some problems with how it worked and vendor lock-in. We decided to wait to see if we could get the virtualization without being locked in to a small vendor."

IBM became the first large vendor to embrace virtualization fully with its SAN Volume Controller (SVC), introduced in July 2003 as a network appliance or as a blade within Cisco's MDS director-level SAN switch. IBM has made considerable headway with the SVC since last August, when it added the ability to manage arrays from Hitachi Data Systems, HP and EMC; the company announced its 1,000th customer this March.

Hitachi has since rolled out its TagmaStore array-based virtualization, and Sun its StorEdge 6290 controller/array system. And EMC hit the market in May with its Invista virtualization software, which runs on Cisco, Brocade and McData director-level switches.

This is all good news for users, who are struggling with explosive growth in storage coupled with the need to better manage stored data because of compliance pressures.

"Storage is going crazy. We see it going up 25% to 30% a year right now," says Al Todd, senior vice president of IT at Pacific Capital Bancorp, a regional bank in Santa Barbara, Calif. "We can't get enough data on customers - we want to know their shoe sizes, what they had for breakfast this morning, everything. But the problem is, how are we going to manage it?"

Pacific Capital has 23T bytes of storage located around the company, housed mainly in IBM and EMC arrays, Todd says. "We didn't know how much capacity we had or how much we were using - we just kept throwing more disk at stuff and didn't manage it," he says. In February, the company decided to implement Hitachi's TagmaStore Universal Storage Platform, a large array that virtualizes not only its own internal storage but also storage from other vendors plugged into the back end.

With TagmaStore, Pacific Capital preserves its investment in IBM and EMC arrays while getting full visibility into all back-end storage and significantly simplified provisioning of storage overall. "We've attached our core banking system, our data warehouse and our online bank system," he says. "Now . . . we can see exactly what we're using and exactly how we're going to tier the data."

Unlike the network-based offerings from IBM and EMC, Hitachi's TagmaStore houses its virtualization within the array, and then uses the array's own connectivity to link to the external multivendor storage.

"We connect external storage to our ports and then [our Universal Volume Manager] software walks the bus, discovers all the LUNs that are attached behind it and presents a cache image to our controller cache," explains Hubert Yoshida, CTO at Hitachi. "This lets us create tiers of storage and migrate data seamlessly between those tiers, on the fly, just by transferring our cache images."

Tiering, ease of management and provisioning were key, Todd says. "The vast majority of our data, say 90% of it or greater, isn't used much after the initial transaction. We wanted to be able to migrate that to cheaper storage in a simple, efficient way, and TagmaStore lets us," he explains. And, "if you need more storage, it's provisioned seamlessly. The applications don't even know."

Virtualization also is simplifying the storage environment at Sonnenschein, Nath and Rosenthal, says Eric Muniz, network operations manager for the Chicago law firm. Sonnenschein recently implemented Sun's StorEdge 6920 as part of an overall data center consolidation project. "We were looking for a storage unit that would allow us the virtualization and management capabilities of a centralized approach and still provide features like remote boot and multipathing," he says.

Talk it up

Tony Adams, IT analyst with J.R. Simplot, in Boise Idaho, recently shared his thoughts on two of the biggest storage trends: management and virtualization in this mini Q&A with Julie Bort, executive editor, Network World Signature Series.


StorEdge 6920 uses similar technology as Hitachi's TagmaStore, but is aimed at more of a midrange market. Sonnenschein currently houses 6T bytes of data, and plans to ramp that up quickly to 16T bytes once it finalizes its consolidation project and gets the 6920 fully up and running later this year. The firm runs an old HP/Compaq EMA12000 array, as well as some HP MSA1000s, to support Microsoft Exchange. This will be seamlessly managed from a central console using the Sun 6920.

Muniz says he likes the idea of doing virtualization in the Sun controller unit vs. out in the network. "Let's say I lose an entire chassis on the switch and I go to rip that switch out," he says. "If I'm doing virtualization in the switch, I've got to know exactly what those zones are and remake them. Whereas the redundancy that's built into the 6920 itself is inherently immune to those issues. I'd have to lose the entire SAN in order for that box to lose its way."

Although Hitachi and Sun chose the array route, users and analysts say the network also is a good place to house virtualization, especially for large-scale implementations.

"IBM and EMC have similar approaches to virtualization in that it's housed in a router in the network, between the servers and the storage," says Stephanie Balaouras, a senior analyst at The Yankee Group. "The router maintains all the routing information and mapping of volumes. It's designed for larger companies that have a lot of heterogeneous storage and a lot of pain around provisioning that storage."

"The network is the right place for us," says Karl Rautenstrauch, storage administrator at a large HMO in Florida that is evaluating storage virtualization offerings from IBM, EMC and Hitachi.

He manages 300T bytes of data across EMC, HP and IBM platforms, all networked via Cisco's MDS 9509 SAN switch. Virtualization would ease management of the various platforms and make them more readily accessible to the various application servers, he says. "We have so much storage available to us, but not every server can get to it" since it's provisioned on a per-application basis. "Virtualization will let us be more efficient and better utilize what we have."

Virtualization at Big Blue

When IBM rolled out its SAN Volume Controller two years ago, it do so as part of a strategy similar to the one the company took with Linux.


Cummings is a freelance writer in North Andover, Mass. She can be reached at


Virtualization at Big Blue CLICK HERE FOR MORE>>>

Learn more about this topic

Virtualization of storage improves utilization


Calculating savings from storage virtualization


Three steps to storage virtualization


A vision of togetherness


Network World's Storage in the Enterprise newsletter

Join the Network World communities on Facebook and LinkedIn to comment on topics that are top of mind.

Copyright © 2005 IDG Communications, Inc.