Page 278 -

249
V
C
C h a p t e r 1 2 : h a p t e r 1 2 : Vi r t u a l i z a t i o n i r t u a l i z a t i o n 249

Storage Virtualization Solutions
Vendors understand the need for streamlined SAN solutions, and they’re introducing new and
ever-efficient technologies all the time. In this section, we’ll take a closer look at some of the
better SAN solutions out there and talk about how they can help you virtualize your storage.

Compellent Storage Center
Storage vendors are seeing the benefits of going green and reacting to market pressures to churn
out smart products that balance performance, power, and consumption. One such company is
Compellent. Compellent offers a number of SAN enhancements with its Compellent Storage
Center 4.0. In fact, Compellent is not only concerned with providing an effective, efficient SAN,
but is also taking strides to address ecological considerations through its products.
The company uses such technologies as the following:
• Automated tiered storage
• Thin provisioning
• Advanced virtualization
Compellent notes that a fully featured Storage Center SAN can save companies up to
93 percent of the power consumption and power costs of storage when compared to
conventional solutions.
For instance, the company observes that a typical 20TB storage system configured with
RAID 10 and utilized at 50 percent might require 274 enterprise-class disk drives. Using
10,000 rpm 146GB drives could consume 6020 watts per year (52,740 kWh). If the company
pays $0.10 per kWh to power those drives, it would cost US$26,370 over the drives’ 5-year
lifespan.
However, a Compellent SAN with its proprietary technologies—thin provisioning,
advanced virtualization, and automated tiered storage—might require just 14 of the same
enterprise-class disk drives configured at RAID 10, and seven 7200 rpm 750GB SATA storage
disks, configured at RAID 5.
This configuration would consume just 429 watts—or 3758 kWh—for a total cost of just
US$1879 over the drives’ 5-year lifespan.
Let’s take a closer look at the technologies Compellent uses to reduce the size of a SAN.

Thin Provisioning
Compellent’s thin-provisioning software is called Dynamic Capacity, and it helps increase
storage utilization, thus lowering the overall number of drives required for a SAN. PART V
Dynamic Capacity allocates storage only when the data is written to the disk, instead of
preallocating storage capacity to volumes before they are used. The result is that administrators
don’t have to overprovision capacity to plan for future growth.
By purchasing and operating fewer disk drives, companies significantly reduce power,
cooling, and real estate costs. If you were to just use Dynamic Capacity, you could reduce
the number of drives you need by 75 percent.

Automated Tiered Storage
We talked about the advantages of tiered storage earlier in this section. Although the
concept of moving less-often used data to slower, less expensive drives is a great idea, it’s
time consuming for IT managers to physically perform.