Small Form Factor SAS Disk Drives Save Money and Help the Environment

Author: Don Jeanette, Sr. Manager, Product Marketing
Fujitsu Computer Products of America

When computers use less energy, they cost less to operate, thereby increasing a company’s profits. It does not get any simpler than that. Fujitsu has once again answered the call to helping companies save money by saving power, while at the same time, helping the environment. Fujitsu is now shipping its third generation 2.5″ 10K RPM and first generation 15K RPM Enterprise hard disk drives. These drives range from 36GB up to 147GB in capacity.

While today’s computers offer higher processor speeds and more memory at a lower acquisition cost than ever before, they cost much more to operate. That’s because while newer server-class computers are smaller and more powerful than before, their greater processing power and increased capacity for storage make them consume more power as they perform their work.

These increasingly powerful processors, larger-scale memory devices, emit more waste heat than earlier models. They have less space in which to dissipate heat, and that heat must dissipate through higher-volume fans. Furthermore, the additional heat dissipated into data centers has to be re-dissipated using more powerful air-cooling systems.

Energy consumption and heat generation are not new problems in the computer industry. Processor, memory, disk drive designers and engineers have consistently reduced energy demand and heat dissipation even as they have increased computer power and capacity. However, increases in user demand have dramatically increased the need for computer processing power and storage capacity, and thus the need for more energy.

The growing level of demand makes expedient solutions of reducing the number of servers, network appliances, lowering the processing power, or storage capacities of computers, unavailable. That leaves open the question of how IT managers can cope with such a dramatic rise in energy consumption and heat generation, and, of course, the costs associated with them.

A Workable Solution

Small Form Factor (SFF) 2.5″ hard disk drives have addressed the problem of higher energy consumption and heat dissipation while maintaining the required high-performance expected from enterprise hard disk drives. These smaller drives use smaller motors and drive arm actuators that use less energy and emit less heat than larger, 3.5″ format drives of equal performance. Their very small size also makes it possible to design computers that contain more of them in the same space that might otherwise house larger format, 3.5″ drives.

The 2.5″ form factor disk drive is smaller in every dimension than the 3.5″ drive. The height is 41% smaller, the width 31% smaller, and the depth is 31% smaller. The resulting overall cubic volume is 72% percent smaller, which makes a substantial difference in chassis design opportunities.

Table 1 shows the power consumed by each of these hard disk drives, and it’s clear that the smaller form factor drive takes substantially less power however it is measured. At idle, the 2.5″ form factor drive takes 65% less power, and when performing 220 I/O instructions per second, it takes 56% less power. The overall current requirements are also less, especially in 12-volt chassis designs.


Table 1: Power Consumption (approx.)


The power consumed by one drive is not substantial, however when you multiply the consumption by the very large number of drives housed in a modern data center, the power savings of the smaller form factor drives is substantial.


Table 2: Power Cost Example (approx.)


Table 2 shows that if there are 1,000 disk drives operating at idle for one hour, and electricity costs $0.25 per kilowatt-hour, then electricity used in that hour will cost $3.20 with the 3.5″ format hard disk drives, and $1.125 for the 2.5″ format hard disk drives. The 2.5″ hard disk drives save $2.075 per hour. That works out to $348.60 per week or $18,127.20 per year, which is a substantial amount of money in any business. The savings are even greater when the disk drives are busy, which they usually are.

There is a major business opportunity to save money, and a major environmental opportunity to use less energy, by substituting small form factor 2.5″ SAS hard disk drives for larger format drives. Not only do they consume less direct energy as they perform their work, but they emit less heat, which saves on cooling costs. They also take up less space, which will allow you to pack more computing power into the same environment without raising your energy use or energy costs.

As previously stated, Fujitsu’s hard disk drives answer the need for high performance with lower power, while maintaining a high reliability of 1.4M hours MTBF. The 2.5″ 10K 3G SAS hard disk drives currently shipping are the third generation being offered. Volumes have increased substantially each quarter over the past two years, and the industry’s strong move to 2.5″ is as aggressive as ever. Fujitsu’s latest 15K RPM 2.5″ SAS offering will help this migration happen even faster. Whatever your performance or capacity requirements are for your SAS 2.5″ Enterprise needs, Fujitsu has a SAS 2.5″ hard disk drive solution.

Fujitsu’s 2.5″ SAS Product Summary:
MBC Series
2.5″ FF, 15K RPM
36, 73GB capacities
1.4M hours MTBF

MBB Series
2.5″ FF, 10K RPM
73, 147GB capacities
1.4M hours MTBF

However energy and cost savings are measured, when you acquire equipment that uses the smaller 2.5″ form factor SAS hard disk drives, there will be about a one-third savings in direct energy usage and the costs that go with it. Other costs and energy use associated with air conditioning will also decrease. Space requirements will downsize in the future when more systems designers redesign their equipment chassis to accommodate the smaller format equipment without wasted space. Ultimately, that will mean more computing power for a given amount of space, and at lower energy consumption and lower costs.

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