Mark Peters, an analyst at Milford, Mass.-based Enterprise Strategy Group, draws a distinction between MAID, a term first used by Copan Systems Inc., and spin-down. According to Peters, MAID systems restrict the amount of storage capacity that can be active at any one time to approximately 25%. Spin-down systems are more variable in how much capacity is spun down according to data usage.
The Storage Networking Industry Association (SNIA), on the other hand, defines MAID as "a storage system comprising of a massive array of (idle) disk drives that are powered down individually or in groups when not required."
"People use the term glibly now, like Xerox or Kleenex," Peters said. Ultimately, Peters said he expects MAID to become so ubiquitous "it won't really matter what the differences are." For more of Peters' insights about MAID and its future, see our
Vendors and products that offer MAID and drive spin-down include:
Copan Systems Revolution Series
Copan was the first vendor to bring MAID to a widespread audience with its Revolution series of virtual tape library (VTL) systems, which have expanded in recent years to also serve as network-attached storage (NAS) disk-backup repositories. Copan's approach to MAID is geared strictly toward the enterprise data backup and deep archiving market, where performance isn't the top priority. Twenty-five percent of the Revolution system can be spun up at any one time; disk drives are not spun up or down individually. Copan's Disk Aerobics feature spins drives up in the background to ensure they remain available.
DataDirect Networks Inc. S2A Storage Systems
DataDirect's D-MAID feature for its S2A disk arrays allows users to spin down entire tiers of disks into sleep mode according to policy, rather than individual drives or RAID groups.
Digi-Data Corp. T2000 Controller Disk Power Management
Digi-Data's approach to disk spin-down would be outside the purest MAID definition -- it spins drives up or down according to activity, so four out of five drives in a RAID group could be spun down, for example, if a user so chooses. How long a RAID group or individual drive should wait before powering down is also user-configurable.
EMC Corp. EMC Disk Library, Clariion CX4 Series, Celerra Series
EMC's spin-down is an add-on feature for its existing data backup and primary/secondary storage disk arrays. The EMC Disk Library 4000 Series is the first to ship with the option; with an upgrade to the Version 3.2 software on DL4000 RAID 6 systems, users can have the system put drives in sleep mode when idle. EMC Disk Library and EMC Celerra NAS are both based on EMC's Clariion disk array hardware, though the feature has yet to become generally available for Celerra or Clariion.
Fujitsu Eternus Series
Fujitsu's Eternus 4000 and 8000 series disk arrays ship with the option of ECO mode at no extra cost to the user. ECO mode spins down disks according to RAID group, and can be used with any drive type, although Fujitsu recommends it only for lower-performance SATA-based tiers of storage.
greenBytes' business model is based on its software modifications to Sun Microsystems Inc.'s open-source ZFS file system, which add power-saving features to the Sun Fire X4540 "Thor" storage server. greenBytes calls these modifications ZFS+. The software bundles deduplication, inline compression and power management using disk drives' native power interfaces. greenBytes also claims that its enhancements to ZFS store data heuristically on the smallest number of disks possible, freeing up more drives to be put into a "sleepy" spun-down state.Hitachi Data Systems Adaptable Modular Storage and Workgroup Modular Storage Arrays
Users of Hitachi Data Systems' midrange arrays can designate which disks should be spun down volume by volume, rather than having the system spin the disks down automatically according to frequency of access. Spin-down is also supported on Fibre Channel disks by Hitachi. The feature, which is formally called Power Savings Storage Service, is an add-on licensing fee for the system that's priced per frame.
Hitachi Global Storage Technologies (GST) Deskstar Disk Drives
For systems integrators, OEMs or do-it-yourselfers, disk drive manufacturers are increasingly offering configurable power profiles in their products. Hitachi GST's Deskstar desktop-class hard drives offer four power/performance modes: normal; unload, which sends heads to the ramp next to the drive if the drive is idle for several minutes; low-RPM for periods of non-use; and standby, which removes power from the disks altogether.
LSI Corp. MegaRAID Dimmer Switch
With MegaRAID Release 3.6, any unconfigured drive connected to a MegaRAID adapter will be spun down after 30 minutes of inactivity. LSI licenses its controller technology to multiple, large storage OEMs, most prominently IBM Corp.
NEC Corp. of America D-Series SAN
NEC's PowerSaver feature for its D-Series SAN products uses server-based scripting to power disk drives up and down. Drives can be powered up and down by volume or disk pool, and critical or performance-sensitive volumes and disk pools can be excluded from spin-down.
Nexsan Technologies Inc. AutoMAID
Nexsan's approach to spin-down in its SAS and SATA disk arrays allows users to customize tiers of spin-down within the box according to policy. Level 1 parks the drive head; Level 2 puts the drive into "sleep mode"; and Level 3 powers the drive down completely. Users can also set volumes to cycle through those levels according to the amount of idle time. So after 10 minutes the drive might go to Level 1, after 20 minutes to Level 2 and after an hour to Level 3.
ProStor Systems Inc. RDX/InfiniVault
ProStor's RDX removable hard drive cartridges and InfiniVault archiving system power drives down inside their cartridges when they're not in use. ProStor licenses the RDX cartridge to Hewlett-Packard (HP) Co., Imation Corp. and Tandberg Data.Seagate Technology LLC PowerChoice
Seagate introduced PowerChoice with its Constellation 2 TB enterprise SATA drive in February. PowerChoice has four levels. With PowerChoice 1 the drive is fully "awake." PowerChoice 2 "parks" the drive head away from the drive platter. PowerChoice 3 spins down the drive partially -- in idle mode, Constellation drives on PowerChoice 3 draw 2.8 watts of power for SAS and 2.4 watts for SATA. PowerChoice 4 spins the drive down entirely.
Xiotech Corp. Emprise PowerNAP
Xiotech added a PowerNAP feature to its ISE and Emprise self-healing disk arrays just this month. Xiotech arrays completely spin down when PowerNAP is invoked. PowerNAP can be managed remotely or locally, and customers familiar with scripting can automate it through applications.
Xyratex Ltd. F6412E RAID Controller and Advanced Power Management
Xyratex's systems, which are sold through OEMs, added Advanced Power Management (APM) software last year that allows the storage end user to identify idle drives and spin them down in groups according to policy. APM also checks spun-down drives in the background to ensure they'll spin up again. Xyratex systems are resold by multiple, large storage OEMs in the market, including BlueArc Corp.'s BlueArc Nearline/Archival Solution.