Although frequently identified with green data centers and commonly offered in storage systems, analysts say massive...
array of idle disks (MAID) technology remains underutilized five years after it first became available."MAID should be playing a role [in green data centers]," said Mark Peters, an analyst at Milford, Mass.-based Enterprise Strategy Group (ESG), who points out that there's no sign of a marked increase in the use of MAID or any disk spin-down. "Although I suspect it's going to become more important as the OPEX crunch hits. More attention is being paid to dedupe [than to MAID] right now." "It's one of the buzzwords out there, but it's not one of those things that customers are racing to turn on," said Greg Schulz, founder and senior analyst at Stillwater, Minn.-based StorageIO Group. "It's become a checkbox thing: 'OK, we have it.' It's just another feature." Copan Systems Inc. created the term MAID in 2004, when it brought out its first massive array of idle disks systems that only used a maximum 25% of its hard drives at once. The idea was to power down drives when they weren't in use, cutting down the data center footprint of denser systems and expanding the life of low-cost SATA drives by spinning them less frequently. Disk spin-down became synonymous with MAID, and is frequently mentioned as one of the key green technology options. Other vendors followed with various levels of spin-down over the next few years, including DataDirect Networks Inc., EMC Corp., Fujitsu, Hitachi Data Systems, NEC Corp. and Nexsan Technologies Inc.
MAID became more intelligent, with various levels of power savings added against performance tradeoffs. For example, Nexsan Technologies' AutoMAID feature allows systems to work without spin-down during times of peak workload and to put them in a suspended sleep-standby mode at other times.But while smaller vendors such as Copan and Nexsan Technologies still market MAID aggressively, it has become just another feature for large vendors such as EMC and Hitachi Data Systems. "Everybody's added some disk slowdown capability," said Arun Taneja, founder and consulting analyst at Hopkinton, Mass.-based Taneja Group. "They don't all drop it down to zero because the restart time is way too long for some applications. But they spin it down to save power where access time is acceptable. It's a balancing act." Added Schulz at StorageIO Group: "While MAID 1 has pretty much gone nowhere, vendors are supporting second-gen MAID, MAID 2.0 or intelligent power management." Copan Systems didn't stand still with the technology as others joined the game. It added the ability to dedupe and replicate data in its libraries, and gave customers the ability to set aside up to 40 drives for a cache separate from the MAID pool. The drives in the cache always spin and increase the ingestion rate for deduplication. But executives at Copan Systems preach that MAID is more than merely spinning down drives. "When EMC and these other guys come out and fight the battle, they've validated the concept," said Will Layton, Copan Systems' co-founder and president of the firm's Federal Division. "But just turning the drives off isn't interesting. You have to do it intelligently and in a new architecture. If you do it on a transactional storage array, you don't get the density advantage. You don't get the true benefits that you would on a MAID array." Layton said government regulations mandating more power savings will help drive MAID, as will the rise of persistent data -- data that's infrequently accessed and not likely to be modified. He points to the broadcasting industry as a hot spot for the technology. Broadcasters keep a lot of data for archives, and Layton said the broadcasters Copan has signed up typically have close to 80% persistent data. But MAID isn't only for archiving. ITV.com, the website for the U.K.'s ITV commercial television network, switched to a Nexsan Technologies SATABeast Xi system for Macs early this year for online storage after Apple Inc. discontinued its XRAID product. Chris Wood, technical engineer, ITV Future Technologies, said Nexsan's AutoMAID feature plays a key role in saving power and cooling in ITV Online's small data center. "We go through thousands of disks a year," Wood said. "AutoMAID saves us a bit of energy, cooling and power." ITV.com installed a SATABeast Xi with 42 1 TB drives in a 4U unit, with expansion drives running the total capacity to 150 TB. Wood set the Nexsan Technologies systems to power down disks after 9 p.m. Disks spin down if they go unused for 60 minutes at night, and the heads are parked after 90 minutes of non-use. "It doesn't make sense to have the unit spinning with 42 disks for 24 hours," Wood said. However, ITV.com's systems aren't always idle at night. There may be a football match or another type of event that requires live footage to be edited and uploaded online. When that happens, the systems need to spin up in a timely fashion when needed. "We haven't noticed any performance issues," Wood said. "We're more than confident our users can carry on working. The time to recycle disk and get performance back is milliseconds. We don't have to worry about dropped frames on our video capture because the disks are spinning up." He added that the ITV.com video-editing platform has saved approximately 40% to 50% on power with AutoMAID, and could save more if the systems were never needed at night. Another MAID customer shows how spin-down can help when combined with other technologies. Keith Bush, senior vice president of information technology at New York City-based MultiPlan Inc., estimates the health care records processor saved up to $1 million by moving data off expensive tier 1 disk with Copan Systems' MAID, deduplication and replication capabilities. Bush said he considered Copan's MAID superior to other competitors he evaluated. "We saw it as 'This is their core competency,'" he said. "MAID gave them a density advantage over the others. They put a lot more disk in a single frame because they don't have them spinning all at one time." ESG's Peters said more vendors should couple spin-down with dedupe and replication to add value. "It could become more connected with dedupe," he said. "Also, they can make it the default rather than a choice for drives that haven't been accessed. As policy-based tiering and migrations, plus remote replication become more prevalent, this would make sense."