Energy savings MAID to order: intelligent power management can ensure performance and reduce electicity use.Ninety percent of all stored data was untouched during a three-month time frame, according to a recent information access study conducted by researchers at UC-Santa Cruz. This study revealed a common but not well-understood problem in data center management: Most data centers run needlessly at full power around the clock because of an incorrect assumption regarding data usage.
A key first step in reducing IT energy consumption is making storage administrators aware that their systems are running at full capacity much more often than necessary. Far too many data center managers are wasting large amounts of money because they think their storage systems need to run at full power 24/7.
In a typical data center, most data requests come between 9 a.m. and 5 p.m. on weekdays. Those 40 hours only account for 24 percent of a week, leaving the potential for energy-efficient approaches to data storage, especially on nights and weekends.
Even businesses with 24/7 operations (such as hospitals) experience significant data center idle time. The central issue is how frequently data is accessed and how quickly the servers can respond-not how often the facility is open.
Many IT managers are surprised to find out just how often their information goes untapped. Data center managers should know their organization's usage patterns to discern how easily savings can be found. Data may need to be kept on hand for long periods of time, but it does not need to consume lots of energy all the time.
Disk drives account for about 80 percent of the energy used in data storage systems. Therefore, addressing that energy consumption is the most important part of the solution.
For many years, massive array of idle disks (MAID) technology has been capitalizing on disk drive idle time to save significant amounts of energy and, in turn, money. Many users have criticized MAID, however, because it has traditionally put inactive disks to sleep and sacrificed fast response times.
In response, a new breed of MAID technologies (Greg Schulz, a market analyst at The Storage IO Group, groups them together as "MAID 2.0.") takes advantage of idle time to save energy without sacrificing performance. Herein lies the real breakthrough in green data storage.
According to Schulz, "MAID-enabled devices are evolving from first-generation MAID 1.0 where hard disk drives (HDDs) are either on or off, with associated performance penalties, to second-generation MAID, or MAID 2.0, implementing intelligent power management (IPM). With IPM-enabled MAID 2.0, instead of HDDs being on or off, there can be multiple power-saving modes to balance energy savings with performance and availability needs."
By multiple power-saving modes, Schulz refers to user-defined settings such as these examples:
Level 1. After 15 minutes of inactivity, the read/write heads will automatically be unloaded.
This simple step, transparent to the user, enables energy savings of approximately 20 percent. It maintains a sub-second response time without a power spike for the first I/O request. All subsequent I/O requests are handled instantaneously.
This setting signifies the fastest response time, while still enabling energy savings. For busy organizations such as hospitals, this feature provides fast access to patient records but can achieve energy savings when there are idle periods.
Level 2. After 30 minutes of inactivity, the speed of the drive platters will automatically be reduced to 4,000 RPMs. The first I/O request will be handled within 15 seconds and all subsequent requests will be handled instantaneously. This level achieves at least 40 percent energy savings and is generally used for data that is occasionally, but not frequently, accessed, such as archived word processor files, spreadsheets and presentations.
Level 3. After 60 minutes of inactivity, the disk drive is placed into a light sleep, yet is still able to respond to an initial I/O request within 30 seconds. As in Levels 1 and 2, subsequent requests will be handled instantaneously. Level 3 enables energy savings of 60 percent or more and is ideal for the long-term archiving of fixed-content data, such as e-mails, financial records and medical tests. Government regulations mandate that many of these files be kept anywhere from decades to an infinite length of time, so organizations need to keep them on hand even if they are not regularly accessed.
In addition to enabling substantial reductions in energy costs, MAID 2.0 technologies are also easy to use. They adhere to the "set it and forget it" philosophy. After a few simple mouse clicks by an administrator, the energy savings take place automatically and dynamically without any additional human intervention.
With cost reduction now a major focus, data center managers can be expected to look at how frequently their data is idle. They will find that it goes untouched much more often than they think. They will also discover that MAID 2.0 technologies can help cut energy costs by 20 percent to 60 percent or more, without impacting performance.
Bob Woolery is senior vice president of marketing for Nexsan Corp., Thousand Oaks. Calif.