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Scalable storage systems: Examining scale-out NAS

Scale-out NAS systems can accommodate data growth simply by adding more capacity and processing power.

"Coping with rapid Data storage growth has been at the core of effective storage management since the advent of...

the Internet. If you look for the root cause of challenges in storage management operations -- backup/recovery, disaster recovery (DR), retention, governance and so on -- all are complicated by unpredictable and sometimes explosive storage growth requirements. The storage solution architected based on today’s parameters can become problematic within just a year and downright unacceptable within two years. Many organizations experience data growth rates in the range of 40% to 100% compounded annually, which translates to a growth rate of approximately 2% to 6% per month. So it’s easy to see how a system in perfect balance in January can be showing the strains of added capacity by July.

Digging deeper, the growth culprit is almost always unstructured data, or data stored as files. The unstructured data growth rate is often 2x to 3x that of structured data. These files can range from very small text files that are just a few KB in size up to large geophysical image and video files pushing terabyte dimensions. Network-attached storage (NAS) is almost invariably the repository used for file system storage due to its ease of deployment, ability to serve multiple environments simultaneously (i.e., CIFS and NFS) and relatively low cost vs. a storage-area network (SAN).

Most NAS deployments fall into the “traditional” category where a “head” (or set of heads) provides access to the back-end storage. These systems connect to IP networks and perform all the file storing, access and management. When more front-end connectivity or performance is required, larger heads are installed. When more storage is needed, drives are added to the back end. The challenge for traditional NAS is that the heads and back-end arrays top out at some point. The IT organization is then compelled to deploy additional, separate systems. Over time, this creates “NAS sprawl” in which numerous systems must be independently managed. As a result, management effort scales in proportion to system growth and the economy of scale is significantly diminished.

To solve the sprawl problem, NAS vendors developed what’s referred to as “scale-out” NAS. Scalable storage systems, in general terms, allow for a large number (hundreds or thousands) of front-end nodes (not heads) to be clustered and for back-end storage modules to be added into a single pool that could reach into the PBs. The architectures of traditional NAS and scalable storage systems are significantly different, meaning their applicable use cases are also different. If management of traditional NAS systems is cumbersome for you, perhaps it’s time to consider scale-out NAS as either an alternative or a supplement.



Scale-out NAS explained: At first glance, scale-out NAS systems suffer from a misperception of unremarkable and indistinguishable features. But there’s clear differentiation between products and a rich variety of capabilities to match various requirements. Because nearly all IT organizations have an incumbent NAS vendor, this vendor relationship will be a major factor in winnowing possible solutions. A number of major vendors offer both traditional NAS products and scale-out solutions. Nevertheless, some firms prefer to pursue a best-of-breed strategy with numerous specialized vendors to complement the established majors.

Traditional NAS vs. scale-out NAS: Before choosing a scalable storage system, you’ll need to understand the difference between traditional and scale-out NAS. While traditional NAS is a high-availability architecture, scale-out NAS is clustered, meaning differences in how power and capacity are added and computing resources are distributed. This chart provides a quick overview of traditional and scale-out NAS.

Looking under the hood: Comparing scale-out NAS products: We provide some important questions to ask your scale-out NAS product vendor regarding nodes, operating system, file system, system architecture, storage and software.

Consider scale-out NAS if . . . : Has management of your storage environment simply reached a point where manpower is stretched to an unsustainable level? Read our checklist to see if it's time to move to a scale-out network-attached storage infrastructure.

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