There's an old saying that's regrettably true. The first NAS box installs without a hitch, but the more filers you install the more your problems grow. Consolidating NAS brings huge benefits to your storage environment: reduced management activity, improved performance and increased storage capacity. Plus it frees data center floor space.
There are four basic ways to consolidate NAS data:
- The traditional approach, where you buy bigger and better versions of the NAS gateways and/or integrated NAS filers you already own.
- Clustered file systems, which provide high-performance access to file system data for companies with large computer clusters.
- Parallel file systems, which are similar to clustered file systems, but provide concurrent access to a single file across a number of nodes operating in parallel.
- NAS aggregators that can be used to consolidate data across a number of distinct NAS filers (both gateways and integrated NAS).
Gateways are good for organizations that have SAN infrastructures and want to consolidate their NAS data onto SAN storage. All major NAS vendors provide tools for data migration from their NAS storage to their gateway products. Furthermore, support is available for all NAS protocols and most OS environments. Although gateway performance and capacity are good, they fall short compared to some of nontraditional alternatives. Gateways provide more flexibility and scalability than integrated NAS boxes. For example, if you just want to upgrade back-end storage performance, you can do that separately from the NAS front end with NAS gateways.
Integrated NAS boxes
If SAN storage support isn't a requirement, a NAS appliance with a NAS front-end and back-end storage integrated into one unit may suffice. It may be much easier to configure an integrated product than a gateway product because there are no SAN configuration issues.
Clustered and parallel file systems
Clustered file systems operate across multiple nodes (generally more than eight) and use off-the-shelf hardware and/or standard operating system software. The nodes can be specialized (i.e., metadata nodes and storage nodes) or generic, supporting both metadata and storage services. Although some products mentioned in the previous section support two to eight NAS box clusters for high availability, none of them do this to quite the extent available from clustered or parallel file system products. A true clustered or parallel file system scales performance linearly as the number of nodes increases and provides access to the same data across all nodes.
Clustered file systems are good for companies with large computer clusters that need high-performance access to file system data. One advantage of these products is that performance can be dialed up almost as high as you want by adding nodes to the cluster. However, they may not be as useful for Windows users, since some have limited (or no) support for CIFS.
Parallel file systems are similar to clustered file systems. They provide concurrent access to a single file across a number of nodes operating in parallel. This requires file data to be striped across multiple nodes, as well as special client software to process all file parts simultaneously. Companies with large computer clusters can take advantage of the massive performance scalability inherent in these products. It's important to check which operating systems a parallel file system supports, as there may be some limitations outside of Linux.
This new class of storage products provides an aggregated view of multiple, heterogeneous NAS boxes. These products provide a single GNS over all file systems for a set of NAS boxes. NAS aggregators, also called network file managers, are great for companies consolidating NAS data from different vendor NAS products or retaining multi-vendor NAS configurations. The main advantage of these products is their support for a single namespace across all NAS boxes under their control. Their drawback is that they add another box (and overhead) to the storage environment, one that needs to be installed, configured and maintained.
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About the author: Ray Lucchesi is president of Silverton Consulting.