Getting the Most Out of MAID

Could MAID-based storage systems be the answer to users' power and cooling problems, or is the technology just another management headache for IT?

The idea behind MAID (massive array of idle disks), which is championed by suppliers Copan and Nexsan, is that SATA drives used within the system can be powered up and down to save energy. (See Summer Storage Survival and Will New Head MAID Clean House?.)

MAID systems typically use a small number of spinning disks that serve as a cache for a set of non-spinning, passive disks. (See Copan Pushes Power Savings, Copan Validates MAID, Copan Signs DDS, Copan Gets New MAID, Time Warner Cable Picks Copan, and Nexsan SATABeast Roars .) If a data request is not found in the cache, the appropriate passive disks are powered up.

Though MAID's been around for awhile, it's gaining higher visibility as users face spiraling power costs and space limitations. "One of the most critical advantages of MAID-based systems is that power, space, and cooling consumption is drastically reduced," Taneja Group analyst Arun Taneja says. "If you look at some of the Wall Street guys, they are totally maxxed out in terms of space." (See Acid Rain & Colo Crazies and Skype Takes Pro Mobile.)

At this stage, specific figures on the market penetration of MAID remain unavailable, although it appears that it is still early days for the technology, even after a few years on the market. "I think it would be fair to assume that the numbers are in favor of the non-MAID side at the moment," quips Taneja.Neither Copan nor Nexsan will say how many actual customers they have, although they have some to put forward: The U.K.'s Wellcome Trust Centre recently deployed Nexsan's SATABeast MAID arrays to support its genetic research, and Copan lists the San Diego Supercomputer Center amongst its clients. (See Wellcome Trust Picks Nexsan.)

What is the future of MAID? That's the biggest question of all. As with any new technology, there appear to be sufficient benefits to have snagged some high-profile evangelists. But sources say you need to look before you leap, and users need to think seriously about how MAID will work for them. With this in mind, we have compiled a list of top tips for deploying MAID-based systems:

Test for power savings.

MAID vendors claim that turning off some disk drives can offer major power savings, potentially shaving as much as three quarters off a user's energy costs. This equation has already struck a chord with at least one user, Memphis, Tenn.-based Baptist Memorial Healthcare. (See Baptist Memorial Healthcare, Baptist Memorial Picks Copan, and Copan Manages 2-Plus Pbytes .)

The health care specialist, which uses MAID systems from Copan, is seeing major power savings. "Because only 25 percent of the disks are spinning at any one time, you're only paying for power and cooling for 25 percent of the disks," says systems administrator Hal Weiss, pointing to one of the biggest current issues plaguing IT managers today. (See Beating the Heat in IT, Big Blue Launches Big Green, and HP Maps Greener Data Center.)Weiss won't specify how much he's actually saving in power, but he insists he's using 75 percent less power than he'd otherwise require. That said, his results will differ from yours, sources say. The actual amount of power saved is equivalent to the amount of disk space that's subjected to the MAID equation. Only a live test will reveal what can be expected in actual savings for a given installation.

Prepare to meet resistance.

Despite the apparent benefits of the technology, persuading other parts of your IT organization that disks should be turned on and off may take some doing.

Baptist Memorial Healthcare's Weiss, for example, admits that many IT managers find the concept of MAID a difficult one to grasp. "People think that if you turn a disk off, it won't come back up again," he says, admitting that he gets nervous whenever his team turns off some of the 15- and 16-year-old VAX drives within his infrastructure.

Weiss insists MAID doesn't give him a twinge, but he says many IT managers still perceive a risk in powering disks off.These sentiments are echoed by Taneja. "Anytime there is a drastically new technology, there are a lot of people who will hesitate going there," he says. "I would definitely put MAID in that category -- it's a totally different [disk-drive] concept."

Given the potential arguments against MAID, it's advisable to prepare to counter them carefully in any proposal.

Evaluate alternatives.

MAID is up against a slew of competing technologies, including tape, de-duplicating VTLs, SATA technologies, and optical disk. (See Sun Offers New VTL, Smart Intros SATA SSDs, and Users Open Up on Optical.) Experts say it's vital to explore the pros and cons compared to MAID.

Most analysts concede, for instance, that performance is the weakness of MAID compared to other disk-based technologies. Since disks must be waked up and spun in response to an access request, the performance won't match that of already spinning disks. For many users, speed of access to data is critical, which means that MAID is a much more viable option for secondary, as opposed to primary storage.With this in mind, StorageIO Group analyst Greg Schulz urges users to think seriously about how MAID will fit into their infrastructures. "Understand what the performance impacts are, particularly if you need to recall large amounts of data quickly," he says, explaining that this is particularly important when considering disaster recovery audits and complex data searches.

Schulz also warns IT managers to think beyond the apparent power benefits of MAID. Bandwidth per watt consumed by MAID should be added to environmental footprint in terms of capacity per watt to factor the potential savings or costs. Floor space required and the availability of management tools should also be considered, he notes.

In some cases, other techniques may prove more effective. "For deep archiving, where data is not going to be accessed very often, it's still very hard to beat the economics of magnetic tape, particularly when it comes to power consumption," Schulz asserts.

Make monitoring a priority.

With disks typically idle for long periods within a MAID system, users need to ensure that these will work as needed when they are finally called upon. "Make sure that the system periodically exercises the disk to determine its health," advises analyst Marc Staimer of Dragon Slayer Consulting, adding that users should ensure that data can be moved elsewhere if there is a problem with a disk.Copan uses software called disk aerobics to monitor idle disks on its systems, and Nexsan also offers software that can check whether the disk has been corrupted.

Intriguingly, HDS, which is said to be looking into MAID, recently highlighted monitoring issues as a major drawback of the technology. In a blog entry last week, HDS CTO Hu Yoshida explained that the vendor does not currently offer MAID "due to concerns over the inability to monitor the health of the disks during idle periods."

Despite a number of calls and emails from Byte & Switch, HDS would not elaborate on its MAID stance, prompting analysts to identify a case of sour grapes. "If they do not offer it, they talk down about the technology," says Staimer.

StorageIO Group's Schulz says that he is also not surprised by HDS's reticence. "[It's] the all-too convenient 'the technology is not up to our standards' excuse used by many in the industry to pooh-pooh something that they do not have yet."

Get in on the game plan.With just a handful of vendors playing in the MAID space, it's important to consider the issue of vendor lock-in. So far, MAID is a technique that's limited to vendor-specific hardware and software.

There's also a limited range of products from which to choose. Besides Copan and Nexsan, Fujitsu and NEC are also ramping up their MAID efforts at the moment, which makes for a tiny, if reputable, elite of suppliers. (See Fujitsu Adds NAS to Eternus and NEC Intros D-Series.)

Given these limitations, it's smart to set up a solid long-term relationship with a MAID vendor, one that includes roadmap exposure and the potential for discounts based on trials of new features and functions.

Baptist Memorial Healthcare's Weiss says there's at least one key area where he would like to see MAID drives enhanced. "I would like to see them double-ported in the future," he says, explaining that Fibre Channel drives typically have two controllers per drive.

By using two controllers, Weiss says that he would get a crucial layer of redundancy added to his systems. "If you have a problem with a path to that disk drive from that controller, you have got a second path."James Rogers, Senior Editor Byte and Switch