Opinion: Thinning out wasteful storage

Availability of storage systems that offer thin provisioning is expanding

When consulting for organizations with large amounts of storage, almost invariably, we find significant quantities of overallocated or underutilized storage. Remediation exercises to "right-size" and "right-tier" this excess capacity can result in substantial savings, although the effort to do so is not without its own challenges. After repeatedly witnessing type of this situation, two fundamental questions come to mind: Why is storage consistently overallocated, and more importantly, what can be done about it?

As to the cause, there is no single reason. Part of the problem stems from an inability to accurately forecast demand, as well as the lack of efficient provisioning and handoff processes from storage administrator to systems administrator to database administrator to application owner. Add to this mix a very limited accounting capability. In an environment with hundreds or thousands of applications, it's hard enough to carve out and allocate volumes, much less apply rigor and control over how efficiently those volumes are being used.

The problem is somewhat analogous to that of server underutilization, where virtualization technology has spawned a consolidation revolution. While storage virtualization continues to advance, one aspect of virtualization that is generating considerable interest is thin provisioning. Unlike the traditional fixed preallocation of storage, thin provisioning records the total allocation request but actually metes out storage dynamically as it is actually written. The result is a pooled approach that, while not new to computer science -- think paging or swap allocation methods -- has only recently been applied to storage.

Availability of storage systems that offer thin provisioning is expanding. 3PARdata Inc., whose name has been most closely associated with this technology, and Compellent Technologies Inc. have been attracting customers. And other vendors, such as EqualLogic Inc., have added thin provisioning functionality. Among the larger vendors, Network Appliance Inc. has been offering its FlexVol capability since the availability of Data OnTAP 7G over a year ago, and more recently, Hitachi Data Systems Corp. -- already a strong virtualization proponent -- introduced Dynamic Provisioning, becoming the first of the high-end SAN vendors to offer this feature.

Thin provisioning is not without its challenges. Spikes in storage demand can wreak havoc in situations lacking appropriate planning and monitoring, so application data usage profiles must be understood before assigning thin provisioned storage. Also, traditional cost-allocation mechanisms are somewhat disrupted by the thin provisioning model. In many circumstances, however, thin provisioning can play a major role in reducing or eliminating the waste incurred through the storage allocation process and thereby shrink consumption and boost utilization dramatically.

Jim Damoulakis is chief technology officer of GlassHouse Technologies Inc., a leading provider of independent storage services. He can be reached at jimd@glasshouse.com.

Copyright © 2007 IDG Communications, Inc.

Shop Tech Products at Amazon