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A closer look at NAS virtualization: administrators can create storage pools and tiers more easily in a virtualized environment.

Virtualization literally comes in all shapes and sizes, but because users and administrators enjoy an inherent feeling of confidence that comes from knowing where their data lives, network-attached storage (NAS) virtualization is often treated differently from other forms. NAS virtualization tends to upset that sense of place and ownership.

To a varying extent, NAS islands exist in every IT organization. While consolidation does not imply or resolve management or provisioning consolidation, it does offer an opportunity to provide seamless data access under a single namespace. End-users benefit from not having to map mulitiple shares from different resources-these are masked behind a single presentation layer: the virtualization appliance. No longer does the IT administrator have to worry about mapping or mounting a long list of network drives from different tilers.

The key benefit of virtualization appliances is data mobility. Data mobility in a traditional environment is a double-edged sword. It allows the consolidation of various shares onto a single location and applies a single set of policies on it; however, a single human error when relocating data from one resource to another can have a ripple effect on the environment. Enter the virtualization appliance, which is able to seamlessly move data between physically separate resources without user downtime or reconfiguration.

Data mobility in a virtualized environment allows the administrator to create storage pools and storage tiers. Data classification policies can then be applied to relocate data from one tier to another, depending on the retention or access policy for the file type.

NAS virtualization also provides the ability to replicate data to or from a remote location using a single mechanism. It allows the IT organization to move away from a per-vendor, per-product solution to something that works across the board (i.e., regardless of the number of physical resources, all replication occurs within the appliance). As a result, the two copies of data are maintained using a single console.

NAS islands today suffer from the "weakest link" phenomenon-the least secure resource in the environment can be a gateway to a security nightmare. In a virtualized NAS environment, a single security policy can be applied to the entire environment, because all access is controlled via the virtualization appliance.


Global namespace is a term that is associated with NAS virtualization. What it really means is the ability to provide a single unified view of NAS resources. In user terms, it is the creation of a virtual but unified directory structure where all resources are under a single parent directory, eliminating the need to have separate mount points for individual resources.

In technical terms, most vendors tout the use of a virtual file system that forms the foundation of the entire NAS virtualized landscape. The virtual file system allows objects from physically disparate resources to be merged and appear as one to clients or users.

One relatively new aspect of NAS virtualization is the ability to abstract Internet small computer system interface (iSCSI) resources, as well. Almost all NAS vendors offer iSCSI with their NAS appliances--the iSCSI logical unit (LUN) resides on the file system as a special file.

For example, a 100-GB iSCSI LUN would reside on the file system in the form of a 100-GB file with special attributes. If the virtualization appliance treats this LUN as a special file and represents this LUN via its own network ports as an iSCSI LUN, all of the features of virtualization--data mobility, migration and security--can be "mapped" in the same fashion as file virtualization.

Most NAS vendors have some form of virtualization capabilities available in their product portfolio. Using a virtualization appliance from the same vendor as the attached physical resources has some benefits, especially related to integration, support and manageability.

If the goal is to consolidate multivendor, multiplatform NAS islands into a single unified space, however, the evaluation should be based on the interoperability matrix and not, for example, a single vendor solution.


The other important consideration is scalability. How many physical resources can the appliance support? What about the total amount of data and the number of files? Keep in mind that file-sharing environments tend to serve many small files, sometimes millions. Find out if the appliances being evaluated have any hard limits.

How integration of the new solution is planned with the existing backup environment is critical to a successful implementation. Rarely is implementing a new backup solution to support a virtual NAS environment a wise idea. Implementing a new backup solution to support a new technology is a "one-off" and introduces a risk to the storage environment because staff now has to maintain two disparate backup environments.

Part of this decision also rests on how quickly data can be restored in the event of a user error or a catastrophic component failure. Finally, ensure that the virtual filer metadata is backed up independent of the actual user data and can be restored in the same manner.

The evaluation of a NAS virtualization appliance should factor in the level of integration required to make it work with the existing backup environment with little or no additional investment. If there is a single authentication infrastructure across the environment, whether it is lightweight directory access protocol or Active Directory, ensure that the virtualization appliance not only supports but fits in nicely with this authentication mechanism. A "veiled" new NAS environment will need to seamlessly migrate from the old one with user profiles and permissions intact.

If security is paramount to the infrastructure, check to see if the appliance supports encryption at source and in motion. Confirm that the appliance will fit well within current security parameters.
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Copyright 2007 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Special Focus: Storage; network attached storage
Author:Nadkarni, Ashish
Publication:Communications News
Geographic Code:1USA
Date:Jun 1, 2007
Previous Article:Is critical data protected?
Next Article:Infiniband and SAN performance.

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