The concept that guides storage and server virtualization is similar, but storage vendors point out the differences between both technologies and provide steps on what IT managers need to do before implementing storage virtualization.
Saravanan Krishnan, Hitachi Data Systems's Asia-Pacific director of storage platform at the solutions and products group, explained that storage virtualization is achieved by bringing together internal and external heterogeneous storage into a single pool with well defined storage tiers, allowing data to be moved between the tiers.
The concept and benefits of storage and server virtualization are the same, Krishnan said in an e-mail interview, adding that virtualization technology is not new and has been in existence since the invention of mainframe.
Eric Goh, managing director of EMC Singapore, further noted that to achieve a dynamic storage system to complement the dynamic virtual server infrastructure, storage must move beyond simple consolidation into virtual storage which allows storage resources to be aggregated and virtualized.
He shared that storage virtualization can be achieved through software deployment either by a host-based or switch/array-based method. "Host-based method requires a software layer to direct the requests while, on the other hand, for the switch/array-based method, fiber channel comes in between the host and storage and acts as a switch that virtualizes the requests," Goh said.
In an e-mail interview with ZDNet Asia, Ng Tian Beng, vice president and managing director for consumer, small and medium business at Dell South Asia and Korea, noted that both server and storage virtualization involve pooling resources together by creating a virtualization layer at the server or storage layer.
However, Ng pointed out that both technologies are independent and different. Server virtualization does not extend to storage, he said, but noted that more organizations will adopt storage virtualization on top of server virtualization as they start to understand the benefits of end-to-end virtualization.
Goh also pointed out that storage virtualization is more effective and efficient for large storage environments. Otherwise, IT managers should consider server virtualization with internal storage disks, he said.
In previous interview with ZDNet Asia, HDS' chief economist David Merrill acknowledged that storage virtualizatiothaws not as popular as server virtualization, but said the latter would drive adoption of the other.
According to Ng, server virtualization is seeing faster adoption because it was introduced much earlier than storage virtualization and is "highly standardized". "The birth of storage virtualization came with many different companies providing varying degrees of virtualization for storage, which resulted in a fragmented market with no standard definition of capabilities," he said.
EMC's Goh noted that servers typically garner more attention because end-user applications sit on them, increasing their visibility. "However, this should not discount the fact that storage array is just as important a component as servers in an IT infrastructure, especially since all critical data are stored in arrays," he said.
Server virtualization is also easier to deploy than storage, requiring only the implementation of additional software, he added. Storage virtualization, in comparison, requires a thorough review of the overall storage architecture and other additional components, he explained, noting that things can get more complicated when dealing with a multivendor environment.
Paul Haverfield, principal technologist at Hewlett-Packard Storage for the Asia Pacific and Japan region, added that both technologies are quite different and require IT staff to develop new skills to handle the complex systems. Therefore, he suggested that a
Trade-offs for storage virtualization
Goh warned that due to the complexity of a multivendor storage environment, storage virtualization--if deployed wrongly--may affect performance, efficiency and coherence.
"Storage virtualization for data and applications stored in geographically dispersed data centers can be a challenging task. This would involve a huge amount of manual tasks and physical transfers," he said. "At the same time, applications have to come to a standstill until testing and verification is complete, which is not an efficient process."
However, Haverfield has a different view. In his e-mail, he noted that from his experience, storage virtualization could in some cases be quicker to implement than server virtualization.
He attributed this to storage virtualization being more independent of workloads and applications, while server virtualization requires a significant amount of time needed to test applications to ensure they run smoothly.
Tips for storage virtualization
Before companies embark on storage virtualization, they should first review these three steps:
1. Understand the current storage environment.
Goh noted that IT managers must first evaluate if storage virtualization can help the organization achieve its required goals.
HDS' Krishnan added that companies need to identify and classify applications that will benefit from a tiered storage virtualization strategy. "It is the business needs and applications that drive storage requirements, which in turn guide tier configuration. Most applications can benefit from a mix of storage service levels, using high performance where it is important, and less expensive storage where it is not," he said.
Haverfield noted that IT managers should assess their organization's data requirements, current storage infrastructure as well as expected future needs. Some of the questions they should ask are: "What data do we have? How should it be protected? Are there any regulatory requirements the organization needs to meet, such as archiving data over a certain amount of time?"
Dell's Ng added that assessment services provided by storage vendors can be useful in help IT managers understand their own environment. He noted that at the Dell Solution Center, customers can consult with network and storage specialists who can guide them in asking the relevant questions.
2. Evaluate needs before deciding on requirements for virtualization.
According to Ng, IT managers need to understand how storage virtualization can benefit the organization--not just the technology alone, but also the ROI (returns on investment) in terms of cost and savings.
HP's Haverfield added that by communicating and demonstrating how the organization can benefit in the long term by implementing storage virtualization, IT managers will more likely be able to secure buy-in and support from all stakeholders. This in turn will help maintain interesr in allocating resources for an effective and proactive process, he said.
EMC's Goh said IT managers need to weigh the perceived benefits against the cost of complexity involved in storage virtualization to determine if the effort is worth it. "Otherwise, instead of choosing storage virtualization, it may be more practical for IT managers to consolidate the multiple environments into a single one," he added.
Krishnan noted that IT managers need to align each application to the right tier of storage characteristics such as availability, performance, cost, protection and recoverability, and retention and compliance. "It will be useful to develop a specific map of the individual characteristics of each attribute for every tier. These will be the storage service characteristics an application gets when assigned storage from that tier," he said.
"When defining storage tier characteristics, managers need to observe how applications map to those tiers. The design should be able to accommodate the storage service level requirements of all applications," he added.
3. Develop a vision of the destination.
Haverfield noted that IT managers need to know where the storage virtualization journey will end based on the requirements and expectations on future needs. "For example, determine if the goal is to achieve a private cloud infrastructure, end-to-end provisioning of server plus storage resources or a simplification approach versus a traditional 'siloed' approach," he said.
With the requirements of storage virtualization in mind, Dell's Ng said IT managers should talk to storage vendors with competency in end-to-end virtualization so that the migration can be achieved in a simple and non-disruptive manner.
Krishnan pointed out that IT managers also need to map storage for each application from the appropriate tiers as needed. "For instance, for a company's mission-critical Oracle business applications, primary tier storage is used. However, the backup mirrors and lower priority development copies are run on the more cost-efficient 'less critical' tier. Old records in the Oracle databases can be regularly archived to the 'archive' tier," he added.