With storage needs spiraling upward, it's simply impractical to keep every piece of corporate data on expensive, high-performance Fibre Channel discs.
The practice of tiered storage has emerged as a way to mitigate this expense by keeping mission-critical data on the fastest disc platforms while relegating less valuable data to slower and less expensive storage, such as SATA disc or even tape. In most cases, an organisation will establish and maintain several different storage tiers. But, organising corporate data into tiers is hardly straightforward.
First, data must be classified to understand the relative value of each file or file type. Data types that are only infrequently accessed, such as email, are often indexed and stored with automated archiving tools. Data then has to be migrated between storage platforms so that it can be stored according to its classification. This Buying Guide covers the major product considerations involved in tiered storage initiatives. Each chapter offers a set of buying points and product specifications that can help readers identify prospective new tiered storage products. Before we look at specific product categories, let's start by identifying the core concerns when considering tiered storage.
Establish data retention policies in advance. Most organisations are obligated to retain certain data types in order to meet compliance and litigation needs and then delete that data after its retention period expires. However, retention policies are not set automatically -- no software can tell you how long you should keep a piece of data. Instead, retention is defined by understanding the value of each data type and its relationship to compliance. Data migration and archiving tools can then be used to enforce the established retention policies across your storage tiers.
Have a data categorisation plan formulated in advance. Data classification is not automatic -- no software can determine the actual value of data to your own organisation, so don't rely on data classification tools to make classification decisions for you. Data classification is a human process that involves understanding and input from many departments, like human resources, finance and legal. Once you have established the relative value of each data type, data classification tools can then find the data, apply metadata and enforce established retention policies. Experts note that the most successful tiered storage deployments occur when categorisation and retention policies are already mature and proven.
Consider the management impact of additional storage systems. Tiered storage often involves the use of multiple storage systems, and this can sometimes present more of a burden for storage administrators. For example, Tier 1 storage may reside on a Fibre Channel storage area network (San), Tier 2 storage may reside on a SATA network attached storage (Nas) and Tier 3 storage may exist on a content-addressed storage (CAS) archiving system, virtual tape library (VTL) or tape library. For some organisations, the added cost and management overhead imposed by multiple storage tiers can overcome the benefits, and experts note that some large data centers are actually abandoning their tiered storage in favor of a single tier.Set realistic savings expectations. Buy the tool that best fits your needs. Consider the potential for performance improvements. Return to the beginning