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However, for organizations that haven’t embraced the concept, the result is more
expense and more energy usage. For instance, many businesses deploy the fastest—and
most power-hungry—Fibre Channel disk drives in a single tier. All the organization’s data
is in that pool, which is great for the current data, but the Third Quarter Operations
Department Report from 1997 doesn’t need to be on such a system.
Compellent takes the person out of the process with its automated tiered storage
solution, which adds more economical drives to the SAN. The architecture now has two or
three layers of drives, as shown in Figure 12-5.
At the top in tier one are the fast, 15,000 rpm Fibre Channel drives. This is where the
mission-critical data is stored. Beneath it in the second tier are the 10,000 rpm drives. But
most of the data in your system—about 80 percent—is rarely accessed. This data is
relegated to the 7200 rpm SATA drives at tier three.

Boot from SAN
Datacenter power requirements can be further shrunk through the use of Compellent’s Boot
from SAN solution. By maintaining an operating system boot volume on the SAN, rather
than the server, you have no need for server-attached disks. By eliminating the need for

Tier one:
15,000 rpm drives for
mission-critical information

Tier two:
10,000 rpm drives for less
critical data

Data in a tiering system is
moved to slower, less Tier three:
expensive drives as it is 7200 rpm drives for
accessed less frequently. rarely accessed and
archived data
FIGURE 12-5 Compellent’s automated tiered storage reduces the cost of drive acquisition and
operation.