Tiered storage: new strategies match new demands and opportunities

Computer Technology Review, March, 2004 by Kevin Honeycutt

The world of storage is changing, and end-user IT departments need help in planning new strategies to match the new demands and to take advantage of new opportunities to use storage resources more intelligently. One of the most promising new directions involves solutions that combine the characteristics of multiple storage resources in a single managed system. This approach promises to offer concrete help for a large number of different storage issues that are all too familiar to IT departments.

One of these is the fact that the demands on storage continue to increase. Data keeps growing in volume, and it's becoming more valuable to more different parts of the enterprise. The millions of files managed by the typical large organization contain customer records, documents, drawings, images, reference material, messages, etc. Used the right way, that data can give organizations competitive advantages--ways of providing their customers with better products and faster service. Part of what that means is that protecting the data, retaining it over time, and making certain that it can be accessed quickly when needed has become a critical issue for the entire IT team.

A second is that the idea of protection itself has also become more complex. People have recognized for some time that their data is in danger not only from natural disasters but also from computer viruses, human error, and malicious acts. But now they are being forced to contend with a whole new set of cost factors, as regulatory agencies demand that users add legal requirements for protection, retention, and recovery of data to the existing set of business requirements.

And finally, the kind of economic pressure IT organizations face is changing. Companies are recognizing that, over time, the cost of capacity itself is much less important than the cost of managing their systems, and organizations are placing a premium on solutions that can, in the long run, free the IT staff from lower-level management jobs and allow them to add higher levels of value.

The Multi-Resource Storage Environment

A key concept that is helping IT departments deal with the complexity of managing data in the face of these pressures is the idea of combining different kinds of storage resources in a single managed system. The basic idea is simple: Use different resources to provide different kinds of access, retention, cost and protection characteristics and match the resources to the right kind of data. The goal is to be able to make sure that the data can serve all of its various uses in the most efficient way, while making the most efficient use of physical and human resources.

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Behind that simple-sounding idea, however, is a complex set of management tasks that requires recognizing different kinds of storage resources, creating a storage environment that combines them, automating the movement between them, and providing access to the data from the different locations. In the past, the term "tiered storage" has sometimes been applied to multiple resource use, but that term is really something of a misnomer since it suggests a fixed hierarchy of storage locations through which data is always passed. The newer multi-resource systems operate very differently. In them, the various storage resources tend to sit side by side, and access can be provided directly to any of them without necessarily moving the data back through different levels. Instead of tiers of storage, there are multiple alternative resources which are used to store and access data based on a changing set of needs.

The kind of managed storage environment can look very different depending on what kind of uses and applications are being served. At one end of the spectrum is the kind of fully unified Data Lifecycle Management (DLM) environment that ADIC's StorNext Management Suite (SNMS) creates. This unified storage environment can consist of multiple kinds of disk systems (performance disk and value disk) as well as tape (both libraries and off-site tape pools). The unified environment is created by file system technology that allows all the files stored to be accessed directly from any location by the applications that have access to the storage environment. Management of data on different resources--migration, copying, movement off site--is automatically managed by SNMS based on policies that allow the access patterns and age of files to map resource use and file management to business value for the data. Policies can be set to include protection of data on different media types as an automated attribute of the managed system.

This data environment provides general-purpose storage and it presents itself as disk to applications using the storage. The hosts look at this pool of storage and see usable capacity--behind it are different disk and tape resources with different access and protection characteristics and policies to move data between them. Because it is based on a fully heterogeneous file system, the storage environment created by SNMS supports multiple server platforms and operating systems, allowing applications designed for UNIX, Linux and Windows systems to share a common pool of automatically managed data. There are several uses for this kind of environment. Specialists have used this kind of consolidated storage pool for managing very large data sets and for sharing data in highly collaborative work environments. IT is now beginning to reach a more general IT audience, as new demands for data management make consolidated storage attractive and as content-aware Information Lifecycle Management (ILM) applications need a foundation to actually map data to different resources.