With companies doing everything possible to conserve cash, conserving power has quickly become an important part of the IT portfolio. No longer is physical server sprawl an option; in terms of both hardware acquisition costs and ongoing energy and cooling costs, the “throw hardware at the problem” crowd is being replaced by people who attempt to virtualize everything and do everything possible to keep that energy bill low.
The right storage solution in the data center works directly toward the green goal, particularly when the storage solution sports the right feature set. Allow me to explain.
The disk shelves themselves
Shared storage itself in the form of a SAN can help organizations reduce their carbon footprint by using less electricity. Consider this: Historically, before the days of virtualization, organizations often purchased physical servers that were built for long-term use. As such, that initial server configuration was more than likely to be overkill for the originally intended solution. That over-engineering generally included the number of disks housed in the server. After all, even though a server was being purchased for a specific task, who knew exactly what would be required in the future?
The result: In general, physical x86-based servers were horribly underutilized, both from a storage and a processing perspective. Even though the server wasn’t running at full capacity, it still required power to run all of the processors originally specified, as well as the disk spindles originally included with the unit.
Fast forward to today. It’s now hard to find a data center that isn’t using virtualization in some form in order to consolidate some of these underutilized servers. To support virtual environments, even the smallest organizations make use of SAN technology. Besides the obvious savings that comes from simply having fewer servers to energize, consider the direct benefits of a SAN. In many, many cases, organizations performing server consolidation tasks can meet their overall technical needs with fewer disks in the shared storage device that powers the data center. As is the case with servers themselves, simply having fewer disks in the data center means that less power is required to run them. Today’s disks are often more energy efficient than older models, too.
We’re at a point now at which there are fewer disks in the data center; perhaps the disks are larger capacity, but it’s likely that the total number is lower than it was when you ran all physical hardware. What could you do to lower that overall number of disks even more?
The first shared storage feature that can help accomplish this task is thin provisioning. In short, with thin provisioning, you can assign individual connected servers or virtual machines enough shared space to meet today’s needs, and configure these shared volumes to grow to a predetermined amount of space as the need for additional storage arises.
How does this help you achieve your green goal? The one thing that hasn’t changed in server and storage purchasing is the need to buy more space than you’ll probably need. Adding space to an existing server has become a lot easier, but it’s still a task that many don’t want to have to worry about. With thin provisioning, you’re able to achieve better overall storage utilization and less oversight is necessary to make sure that individual server volumes aren’t getting low on space.
Better overall storage utilization = less need for additional disks and shelves = less electrical usage.
The final feature that I’m going to cover in this posting is data deduplication. Data deduplication involves eliminating redundancies in data at the storage level. Also known as single-instance storage, data deduplication can have massive benefits when it comes to the amount of space necessary to store data.
Consider this: An e-mail message with a 10 MB attachment is sent to 500 users in your organization. 100 of those users save the attachment to their personal folder, which resides on your SAN. The total hit: 100 people times 10 MB = 1,000 MB or 1GB. While this isn’t a ton of space, repeat this process dozens and hundreds of times across the organization, and you can see how quickly space can be eaten away.
Enter data deduplication. Now, although that file is stored 100 times on your SAN, your SAN is smart enough to look at the file construction and realize that there is a repeating pattern than can be stored one time with pointers replacing the file in the other 99 locations.
Again, this results in a need for fewer disks since less disk space is required. Although it might not directly stave off over-provisioning an initial storage purchase, you might be able to avoid adding another power-hungry disk shelf to your data center.
If you wanted to get to the least power hungry disk solution, you’d just buy a bunch of 1.5 TB SATA disks and stick them in a RAID 5. Obviously, this wouldn’t be considered the best overall option since disk capacity is just as important as overall disk system performance. However, getting close to that disk spindle count/capacity balance will get you a long way toward greening your data center by managing storage alone.
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