Virtualization Technology News and Information
Beware the stumbling blocks in storage virtualisation

Quoting from ComputerWorld

Virtualisation is a means to improved storage management. Depending on the environment, virtualisation can either reduce or add to the level of management complexity.

There are several issues which may arise in a virtualisation scenario. One is the lack of vendor support for virtualised configurations. Another is the confusion over competing technology approaches, lack of standards and fear of vendor lock-in.

Despite these, there are several bright spots in storage virtualisation offerings that seem to be resonating with enterprises and these are being deployed to address specific storage management challenges. Tiered storage and file system aggregation are two such offerings.

Tiered storage: Many organisations excitedly adopted tiered-storage strategies only to become frustrated by additional management complexities that have hindered expected financial benefits. The challenges of diverse management tools and data migration among tiers are two areas where virtualisation can help. One interesting approach is the controller-centric Universal Storage Platform (USP) from Hitachi Data Systems (HDS). The key here is that virtualisation has existed for years at the storage controller layer within the array enclosure and is well-understood. HDS simply extended their controller capabilities to support additional types of arrays beyond the frame boundary. It is now possible to leverage the identical sets of services such as split mirrors and replication among all tiers in a consistent manner behind the same controllers.

File system aggregation: Network-attached storage (NAS) is a technology that has been wildly successful, in some cases, too successful. While people love the ease of setting up and managing NAS appliances, in large shops the number of appliances has created its own management challenges. Issues like laying out shares effectively, migrating among boxes for load balancing, capacity management, and technology refreshes can be complex and time-consuming. The complexity can be reduced through virtualised global namespace technology to aggregate and present a common file system view. Companies such as Brocade Communications Systems with its NuView acquisition and Network Appliance with its Virtual File Manager (OEM’d from NuView) isolate the logical file system structure from its physical layout to simplify these management chores.

Even after deciding on the particular technology to be used, it can still be a challenge to find a storage virtualisation solution that can be deployed in a multi-vendor environment.

Three years’ worth of market hype have not been able to overcome reservations about multi-vendor storage virtualisation.

At Storage Networking World in San Diego this April, customers and industry analysts said there were a number of reasons network executives weren’t rushing out to buy intelligent Fibre Channel switches or appliances that virtualise or pool the storage resources on arrays from different vendors.

“Heterogeneous – that’s a good word,” says Tony Prigmore, senior analyst for the Enterprise Strategy Group. “You have a classic situation where all the branded vendors are going after their installed base. That’s happening with IBM’s SAN Volume Controller; it’s happening with HP, Hitachi Data Systems and EMC. Vendors are just now starting to expand to support arrays from other vendors.”

So far, Hitachi, HP, IBM and Sun are shipping either array-based storage virtualisation or Fibre Channel switches that pair with server appliances to add intelligent services to the storage fabric. Hitachi has an intelligent controller in its TagmaStore array that virtualises the storage resources attached to it. IBM and EMC manufacture server-based appliances that attach to ­Fibre Channel, director-level switches from ­Brocade, Cisco and McData to virtualise storage resources.

All these companies say they support heterogeneous storage virtualisation. Hitachi’s TagmaStore, for instance, can connect to IBM Enterprise Storage Server and EMC’s Symmetrix and Clariion products.

Dave Hill, senior analyst for the Mesabi Group, points to another stumbling block on the way to heterogeneous virtualisation: Customers and vendors want to protect existing assets and investments.


As storage virtualisation continues to evolve, the number of technology options will inevitably grow. It is essential to have a good understanding of the problem that needs to be solved and how a particular technology might be applied to address that problem.

Read the entire article, here.


Published Wednesday, June 07, 2006 6:23 AM by David Marshall
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