may 30

Do away with 'free' storage
Proper cost allocation must begin with accurate storage cost metrics
Computerworld Opinion by GlassHouse CTO, Jim Damoulakis

http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9022001

As IT organizations strive to rein in storage costs, a significant portion of their efforts is often devoted to determining how to best allocate or apportion those costs among the storage consumers within the organization. The goal should be not only to provide a cross-charging mechanism for recouping costs, but also to encourage more efficient usage of storage. The basic concept is that if storage is "free" to users (i.e. no chargeback or accounting mechanism), then there is little inclination to economize or improve utilization, and there is strong empirical evidence to support this.

Unfortunately, determining fully-loaded costs and developing a mechanism to accurately map them back to consumers quickly becomes a complex problem due to the dynamic nature of the storage environment -- systems are being purchased and retired regularly with continual price changes. As a result, organizations often fall back on general percentage-based apportionment that may address the allocation problem but does little to modify behavior because there is no direct cause and effect.

Proper cost allocation must begin with accurate storage cost metrics that go beyond simply the hardware acquisition cost. The first step to establish base cost metrics, including factors such as the following:

• Hardware and software acquisition

• Depreciation

• Maintenance

• Operations

• Data center costs (power, cooling, floor space)

However, to determine the actual fully-burdened unit cost of delivering a given quantity of usable storage at a specific level of service, some additional factors that must be weighed, including:

• Storage capacity lost due to disk formatting (1%-3%)

• Disks reserved for hot spares (4%-7%)

•  Space consumed by a specific RAID layout (10%-50%)

• Space reserved for snapshots (3%)

• Local split mirrors (100%+)

• Remote replicated volumes (100%+)

• Capacity of reserved or unallocated storage (0%-15%)

Driving efficiency and reducing overall costs requires building a multilevel storage services portfolio with discrete performance, availability and recovery characteristics. Being able to accurately justify and explain the cost implication of why it takes 50TB of storage to deliver 10TB of usable capacity for a given service level will raise awareness and perhaps even begin to modify behavior.

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.