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Key questions to ask before investing in a unified storage appliance

There has to be a business justification for investing in the new component and committing resources to deployment, maintenance and support.

If you're a storage manager currently struggling with disparate or competing storage requirements, then it would make sense that one of the many unified system offerings from the major storage vendors appealed to you. Unified storage generally refers to a single product that can provide block storage and file storage simultaneously. That means unified storage products offer an unprecedented degree of flexibility while also promising to drive down storage management costs. But there are some very important considerations that must be taken into account before investing in a unified storage appliance.

First, you'll want to search for a system that is truly unified. A first-generation unified storage appliance was little more than a block storage array with a file system gateway that was "bolted on" by attaching an additional hardware device. Some vendors implemented file system support at the software level, but even in those situations, file system support wasn't native.

Today, there are unified storage offerings that don't require a separate file system gateway. These products integrate file system support into the storage controller rather than requiring separate hardware or software. Even so, some vendors continue to require an external gateway.

Quantifying the benefits of unified storage systems

One of the first rules of IT is that infrastructure changes must deliver some kind of tangible benefit to the organization. As data storage managers know all too well, it's never a good idea to purchase a new technology or tool just because all your friends are doing it -- or because enough vendors have convinced you that it's the "next big thing."

To quantify the benefit of implementing unified storage, benchmark the costs associated with your existing storage system to establish a basis of comparison.

There has to be a legitimate business justification for investing in the new component as well as committing the required resources to the deployment process and ongoing maintenance and support.

If you're planning to replace an aging storage infrastructure, unified storage might be relatively easy for you to justify. Bringing disparate storage systems together simplifies management (which, in turn, reduces administrative costs). Similarly, unified storage tends to be very flexible; so it's possible that this flexibility might help reduce your storage costs. If you believe unified storage might be a good match for your IT shop, then one way to quantify the benefit of storage unification is by tracking the amount of time currently spent on storage management and maintenance costs and how that relates to having separate systems. You should also determine how much storage space is currently wasted or sitting idle as a result of having to separate your storage infrastructure into block and file storage. Keep in mind that the only way to truly quantify the benefit of implementing unified storage is to benchmark the costs associated with your existing storage system so you can establish a basis of comparison.

In the next phase of consideration, you should be able to match your existing system against the potential in a unified system. Unified systems can often help solve capacity and consumption issues that storage pros might be facing with separate systems. Unified storage makes it easier to forecast storage needs and accommodate them as your needs change. Storage managers using unified systems can allocate storage to support various applications without having to consider whether an application will require block or file data access.

Unified systems can also make virtualization simpler by offering storage managers some flexibility in how they store virtual machine data -- simply because they don't have to buy SAN and network-attached storage capacity separately. With greater storage efficiency at the top of so many data storage professionals' priority lists, those reasons are a strong incentive for many storage customers.

Will choosing one vendor help you?

There are a few key questions to ask before investing in this technology. For starters, it's important to consider whether having both systems provided by one vendor will impact your shop. That's because unified storage systems tend to be proprietary, and investing in a unified storage system can lock an organization into purchasing future storage products from the vendor who provided the system.

Some organizations try to avoid vendor lock in at all costs. That's for an obvious reason: If you need to purchase a component and the vendor is the only one who sells it, then the vendor can (theoretically) charge as much as it likes for it.

On the other hand, there are some advantages to vendor lock in. Let's say you purchase all your storage from a particular vendor; (theoretically) you should have an easier time getting support issues resolved because you won't have to worry about vendors blaming one another for the problem.

Considering the application factor

One easily overlooked aspect of the unified storage system evaluation process is your roadmap for line-of-business applications. Today, your organization is presumably using some applications that require file-level storage and others that make use of block storage. (Otherwise, you wouldn't be considering a unified storage investment.)

But it's possible that might not be the case in the future. Applications that require block storage are becoming far more common. Depending on the application set you use, it might eventually be possible to begin transitioning away from file storage.

Avoiding rip and replace

As you evaluate the feasibility and effectiveness of adopting unified storage in your organization, consider that unified storage is not the only option for establishing coexistence for file and block storage. Another option might be to take advantage of storage abstraction.

Storage abstraction tends to be a good option for organizations that don't want to rip and replace their existing storage hardware. By using a virtualization engine or a storage hypervisor, it's sometimes possible to combine block and file storage in a way that achieves many of the same benefits as unified storage, but at a lower cost.

Rating unified storage performance

Finally, and perhaps the single most important consideration for those who might be considering investing in a unified storage appliance, is performance. In short, this issue was a problem in the early days of these systems. The earliest versions often sacrificed performance for the convenience of being able to support a variety of storage protocols.

It's less of an issue today, mostly thanks to improvements in chip design. Even so, in certain situations a unified storage appliance's performance might not match that of a more traditional storage appliance due to bandwidth limitations and the overhead involved in managing multiple storage workload profiles.

Depending on how a vendor chooses to design its unified storage solution, customers may find they have less control over storage I/O than they might with a traditional storage system. Such limitations could potentially lead to degraded performance in some situations, but certainly not in every case. As unified storage technology continues to mature, it's very likely that these limitations will go away.

About the author:
Brien Posey is a Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and healthcare facilities. He has also served as a network administrator for some of the nation's largest insurance companies and for the Department of Defense at Fort Knox.

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