Trends in virtualization focusing on solutions, not technologies - Storage Management

Computer Technology Review, Feb, 2004 by Kevin Liebl

The technology of virtualization is well understood and deployed in many--if not most--Fortune 1000 enterprises, and wide-scale roll out of storage virtualization is gathering steam. Every major storage vendor in the market has blessed the concept of virtualization, despite some initial foot-dragging on the part of some hardware manufacturers. While it may have seemed a threat initially to homogeneous storage networks, most vendors now realize virtualization will instead provide a whole new market for flexible, powerful storage applications in businesses large and small. Virtualization has to come of age.

Trends to Date

Until recently, the storage community has debated the pros and cons of two primary storage virtualization architectures: in-band and out-of-band. Without going into too much detail, a brief overview of each--in terms of infrastructure and scalability, with strengths and weaknesses--should be mentioned.

In-band solutions rely heavily on hardware (virtualization servers) running as intermediaries between the host network and the storage pool. All transactions funnel through this appliance, creating limitations on potential performance and introducing complications in terms of availability. The in-band appliances must have a "fail-over" capability, otherwise, funneling all I/O through a single appliance creates a single-point-of-failure. Additionally, management of these appliances is not always capable of being centralized, so multiple points of management must be accommodated. In contrast, out-of-band solutions, while they may deploy some distributed hardware components to handle metadata, are primarily software-based. The data flows directly from the server to the storage subsystem and, therefore, performance and availability are not impacted. Because of the out-of-band or distributed architecture, centralized management is typically offered.

A Need to Refocus on Solutions

Focusing on the pros and cons of competing virtualization technologies has been, perhaps, a necessary evil in a market where 24X7 data availability and data protection rightly rule supreme. Open discussion of the "best" possible means to provide heterogeneous storage networks is a good thing for the industry and a great service to customers sitting on the sidelines. Switch-based virtualization will, no doubt, raise the level of debate significantly yet again. But both in-band and out-of-band solutions have been "field-tested" extensively over the last two to three years; furthermore, one technology may not be appropriate for all customer solutions. Intelligent switches will no doubt play an even greater role in the coming months. Meanwhile, many shops are living and breathing virtualization on a daily basis in full production environments and garnering huge savings on storage management and deploying superior storage protection. However, many other businesses have a pent-up demand for these same solutions, for applications that only a virtualization platform can provide. As a result, the storage industry needs to refocus now on the tremendous customer benefits virtualization makes possible. Customers are seeking working, proven solutions to many of the following problems.

* Better utilization of disk resources

* High availability and disaster recovery

* Snapshot and replication for rapid recovery

* Central management of storage

Point solutions exist for many of the above storage demands, but customers are increasingly under pressure to consolidate management and applications to save time and money. This consolidation--not just of storage itself, but also of storage management and applications--is what is really driving the new storage market.

The only solution that addresses all of the IT concerns listed above--supporting centralized management--is a solid virtualization product providing the bedrock for heterogeneous storage applications. Only virtualization can solve mirroring enterprise-wide data from disparate data sources, snapshot and replication of entire storage pools or the automatic provisioning of disk across multi-vendor storage arrays. And there appear to be no other answers on the technological horizon.

But buyers beware--not all virtualization is created equally. Corporations seeking to finally consolidate storage and storage management must consider the underlying implementation of a virtualization product, and how disruptive--or non-disruptive--it is to their environment. They must ask the hard questions.

Is the technology mature? The length of time a product has been in real-world production environments is a key indicator of product maturity, as well as the variety and size of the implementations at real customer sites. Since one-size-never-fits-all in enterprise storage, a virtualization solution should be flexible enough to handle SQL, Oracle, Exchange, SAP and a multitude of other data sets and network configurations.

Does it deliver real value? Virtualization alone gives you nothing more than volume management and disk sharing. Does the platform provide a solution for snapshot, replication and mirroring? Does it lend itself to central management and control?