Like all inventions that fundamentally cause positive change, COPAN Systems deserves recognition for the creation of the first Multiple Array of Idle Disk (MAID). As James Burke pointed out in his PBS television series “Connections,” discovery and invention are evolutionary. A new creation depends on what comes before it as a foundation for improvement. COPAN sought to address the issue of managing and economizing the use of energy. MAID positively added value by vastly reducing energy consumption as compared to other disk subsystems. From that point of view, it was a bull’s eye. However, what led to COPAN’s demise was a residual issue their technological approach didn’t take into consideration: application performance. COPAN could have only 25 percent of its drives powered on at any given time. If an application requested an I/O from a RAID array that was powered down, the array that was powered up had to be spun down before the other could be spun up. Ultimately, that built an I/O queue that led to applications timing out. Because of that, the places where MAID could be used were limited. Call that the first generation of MAID, or MAID 1.0.
MAID 2.0 has emerged to deliver the benefits of MAID 1.0 and not suffer application performance timeouts or any other issues. An array that’s fully implemented with MAID 2.0 can be used for any application, any time. The only place you probably wouldn’t turn on one of the three levels of energy savings in MAID 2.0 is in a high-access database that serves a global market that’s running full out 24 hours a day. That may represent 20 percent of all applications. For the remaining 80 percent of all applications, however, MAID 2.0 can save from 20 to 70 percent of necessary energy. Notice I didn’t say you can’t use the array as a primary storage device, because you can—no limitations.
With easy to set up and use policies, MAID 2.0 takes advantage of three power-saving modes, allowing you to select “wake-up times,” which provide energy savings, while also providing acceptable response time to the first I/O.
There are no restrictions for which MAID 2.0 level(s) you configure. You can set all arrays to level 3 for maximum energy savings, or on the other end of the scale, to MAID level 0 for peak performance, or to any combination of power management states that meet your specific needs for wake-up performance, power, and CO2 efficiency. Regardless of what MAID 2.0 levels are set, once the array is awake, it performs at 100 percent full speed until the array detects the next lull in activity and once again starts to put arrays into increasingly deep levels of sleep.
Compared to other offerings with just 42TBs over three years, MAID 2.0 can reduce power and cooling consumption by as much as 69 percent and CO2 emissions from 12.8 metric tons to 3.9 metric tons. Total cost reduction can be as much as 65 percent. These unrestricted values in a world that’s budget- and energy-constrained, along with environmentally sensitive will make a difference, and will become the foundation toward a move that all vendors will pursue.
MAID isn’t even close to dead; in fact, it’s is about to become a mainstay to IT. Here’s what to look for to determine if an array is truly MAID 2.0:
- Accommodates full power simultaneously to all drives
- Dynamically switches among three or more power levels with no restrictions
- No application limitations
- Policy driven by changing application dynamics
- Web interface management.
Never before have we seen a convergence of such pressing matters as the global economic crisis we’re in and the ecological crisis we face. No single action can solve all the problems humanity faces today. However, any savings will be appreciated by your financial controller as well as Mother Earth.