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Four steps for evaluating storage virtualization products

Is storage virtualization for you?

What you will learn from this tip: How to determine whether storage virtualization is a good fit for your environment, and, if so, how to decide which technology and product is right for you.


Virtualization isn't for every storage environment. To figure out whether it's a good fit for yours, you'll have to understand the various types of storage intelligence and where they exist in the network -- i.e. on appliances, routers, gateways or switches -- and determine which implementation approach best suits your needs. Then you can proceed with questions for specific vendors.

1. Storage virtualization functions. Storage intelligence in the network can exist in appliances, routers, gateways and switches. Regardless of where they physically exist in the fabric, these products perform similar functions, including:

  • Data movement for mirroring and migration purposes.
  • Security access including encryption during data movement and at rest.
  • Data protection (backup and copy) as well as retention.
  • Data and storage pooling for improved utilization and simplified provisioning.
  • Hardware assists for server storage tasks including backup to off-load processors.
  • Interoperability between various storage devices for data movement purposes.
  • Wide area data movement, communication interfaces and protocol conversion.

2. Approaches to virtualization. There are two different approaches to implementing storage virtualization:

  • Monolithic processor cards: A cache-centric approach, in which the card is either tightly integrated with the back-end switching engine core crossbar, or simply draws power from the switching device and functions as an application blade. This supports volume managers, remote mirroring and replication, protocol conversion, NAS data sharing and backup with tape emulation. Some products that use this type of virtualization include: the Cisco MDS9000 director supporting IBM SAN Volume Controller (SVC), Veritas Volume Manager and Maxxan Intelligent SAN Switch.
  • Intelligent processor cards: This approach hosts storage virtualization applications to help off-load processing and uses tighter integration in the fabric to offset the negative effects of traditional in-band virtualization. Intelligent processor cards offer more intelligence at the port for high volume, as well as providing common functions without higher cost or reduced performance.

3. Evaluating your needs. When you're deciding whether or not to buy a particular product, ask yourself the following questions:

  • Will the solution be disruptive to your environment or will it integrate smoothly?
  • Does it enhance management activities, or increase the workload?
  • Does it present some form of economical or business-enabling benefit?
  • Does it allow you to achieve objectives or goals such as replacing or enabling something new or something old?
  • Does the solution enable you to adopt and leverage new technology without disrupting existing applications and functions?
  • What are your performance, availability, and capacity requirements?
  • What level of scalability do you need and what problems are you looking to solve?
  • What level of interoperability of your existing technology do you need?
  • Are you looking to eliminate or avoid vendor lock-in?

4. Questions for vendors. Moving forward, ask prospective vendors about their involvement in the evolving ANSI T11 FAIS standard initiative that complements the SNIA SMI-S specification. Bottom line: A storage virtualization solution should work for you and your environment, as opposed to the other way around.

For more information:

Product roundup: Virtualization

Tip: Is storage virtualization here at last?

Tip: Four trends changing virtualization

About the author: Greg Schulz is a senior analyst with the independent storage analysis firm, The Evaluator Group Inc. Greg has 25 years of IT experience as a consultant, end user, storage and storage networking vendor and industry analyst. Greg has worked with Unix, Windows, IBM Mainframe, OpenVMS and other hardware/software environments. In addition to being an analyst, Greg is also the author and illustrator of "Resilient Storage Networks", Greg has contributed material to "Storage" magazine. Greg holds both a computer science and software engineering degree from the University of St. Thomas. 

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