NAS (Network Attached Storage)

Managing the surge of file-based data has become increasingly difficult and complex. Virtualizing NAS through Network File Virtualization (NFV) simplifies storage management and enables administrators to easily address management and utilization challenges without affecting data access.

With NFV, storage administrators need not be concerned about the impacts on end-user data access. Administrators can keep data always accessible and online. This eliminates a major constraint on the storage administration process. NFV lets end-users retain full read/write access to data as it is being dynamically relocated within networked storage.  This dramatically changes unstructured data management and enables administrators to increase capacity utilization, improve performance, leverage tiered storage and ease consolidations all while end-users continue to access and update the data.

Not all Network File Virtualization solutions are equal, however. The key to successfully adopting NFV in your environment is to ask the right questions. There are three key questions to consider:

• What problem does it solve?
• Does it create new problems?
• How does it leverage my existing environment?

First, you need to look closely at what is actually being virtualized. Is it only the location/namespace, or does it include active files? The ability to perform active data management drives many benefits. Performance management applications require an NFV solution that virtualizes active content and can dynamically relocate open files across devices to relieve hotspots. Similarly, managing tiered storage requires a solution that goes beyond “moving dead data.” Simply identifying content that hasn’t been accessed in a period of time and moving this infrequently accessed data, is a small part of Tiered Storage Management. Actively matching content with the appropriate underlying storage device requires the real-time relocation of content and active data management.

The second major question is “Does the solution create new problems?” You will need to know if the NFV product will create worse problems than it solves. For instance, an NFV product’s high management overhead might cancel out other productivity gains, its persistent metadata may or may not be secure, or it may cause a serious performance bottleneck. Look at the product’s total potential benefits in light of all the associated costs and likely impacts. You’ll want to know details on issues like fault tolerance, potential downtime, high availability and performance levels, and restore performance and procedures in case of failure.

Third, you should determine how well a Network File Virtualization solution works with your existing infrastructure. Does it support your existing file systems and all of the software and management tool investments you’ve already made? This is particularly important when it comes to existing backup and recovery procedures. You need to know the specifics of how a given NFV technology acts in the real world with your snapshots and backup applications in your environment. Other key questions include downtime issues, integration with primary storage platforms, support issues with software and virtualization vendors, namespace schema, and protocol functionality.

These questions can be used to segment virtualization approaches and to understand the differences among them.

Approaches to Virtualizing NAS
One popular approach is to combine a proprietary namespace into a virtualization appliance. This delivers many of the benefits of NAS virtualization. It provides file movement with no end-user disruption, but there are several issues to consider. This approach raises many issues with existing backup and recovery procedures to ensure reliable restores. How do you perform a reliable restore of an individual volume or file server?

With this approach, all data access has to flow through the in-band appliance. The scalability concern is not limited to the network hop. In fact that’s the easy part. Scalability and performance concerns stem from the amount of processing and file information required. The larger the environment the more likely the file level information will be written and retrieved from disk greatly impacting latency.

Last, the proprietary namespace introduces risk. The namespace and associated meta data needs to have data protection procedures and high availability to ensure it is always available. If the appliance were to go down, all of the look-up information is contained on the box and all of the clients are mounted to the failed box. How do you recover? And how long will that take?

Another approach is the out-of-band only approach. This does not have the performance or data access risk of the proprietary namespace approach. But without an in-band only capability there is no way to provide read/write access to active data. This solution cannot handle open files, or stale mounts to ensure continuous access. Without the ability to handle open files there is no performance management support or  tiered storage applications. While the embracing of an out-of-band namespace has advantages, this solution is also incomplete.

There are solutions on the market that combine the best of in-band and out-of-band approaches without the downsides. When looking at solutions to virtualize NAS, here’s a checklist to go with some of the detailed questions. First, look for a solution that provides transparency. Not just transparency of file access, but a solution that is transparent to the environment – a solution that does NOT require mount point changes or the deployments of agents on clients or servers.

Second, look for a solution that doesn’t require a persistent namespace. There are many advantages with this approach. It limits risk, limits performance concerns, but also leverages continuing investments being made by large vendors and standards body whether your namespace is Microsoft DFS, Automount, or in the future NFS V4.

Third, virtualization should leverage the investments you’ve already made in your storage infrastructure and management tools. Check for standards support, vendor certifications, and make sure your existing management tools and data protection policies are not adversely impacted.

NFV dramatically changes NAS management. With it you can dynamically relocate data for capacity, performance, or cost reasons without disruption to end-users or applications.

Virtualization approaches differ greatly. The overall management savings, risk exposure, and scalability can range greatly. Virtualization should be a transparent layer in your environment that simplifies – not interferes with your existing environment.  

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