Saving energy based on storage classes with corresponding power saving policies

Abstract

An example of the invention classifies disks drives based on their purpose and associating power-saving policies in multiple classes. The system implements Power On Demand, where a reduced power mode is enabled for every individual component of a storage subsystem. In addition, an embodiment of this invention extends a few power modes used in the prior art and allows almost infinite number of power modes when instructing a disk drive (via its I / O interface such as a SCSI or fibre channel interface) to enter a certain power saving mode. Furthermore, an embodiment of invention teaches a system and methods to save power in a disk system comprising a plurality of disk controllers and a plurality of disk drives, arranged in a plurality of arrays, where each array includes several (e.g., 4-16) disk drives.

Description

[0001]This is a Cont. of another Accelerated Exam. application Ser. No. 12 / 024,015, filed Jan. 31, 2008, to be issued in December 2008, as a US patent, with the same title, inventors, and assignee, IBM.BACKGROUND OF THE INVENTION[0002]Unlike servers with power-down modes (e.g., sleep mode, hibernation mode) such energy-saving modes are not currently used for storage subsystems. The typical storage subsystem powers on all disk drives for all the time, even those drives which are practically never used. Spinning drives is quite costly in terms of energy consumption, hence lots of cooling is needed. There have been initiatives targeting data centers as well as individual machines for lowering power consumption, cooling effort, and carbon footprint, as the market for “green” initiatives in IT is growing with high customer interest.[0003]In a disk system according to prior art such as IBM® DS8000®, IBM® DS6000® and IBM® DS4000® comprise a plurality of disk drives and disk controllers. Di...

AI Technical Summary

Benefits of technology

[0005]The invention implements Power On Demand, where a sort of sleep (i.e., reduced power) mode is enabled for every individual component of a storage subsystem, thereby minimizing overall consumption for the full subsystem and making it flexibly adapting to changing I / O loads. The invention provides a method to spin down the disk drives belonging to groups that are not used for a long time. For instance, RAID arrays without volumes don't need to have spinning drives at all the time, until volumes are actually created. Or, RAID ranks without license key (whose capacity can be increased on demand) do not have to be continuously under full power. Additional types of drives can be found which can selectively be powered down for a longer time without doing any harm to the performance of the storage subsystem. Although powering on represents some loss of time, if powering on is only needed after a long duration (maybe a month) when the first volume is created, this small performance lag may be acceptable given the enormous amount of energy saved in the mean time. Current technologies on the market simply set power on for all the drives or fans.

[0008]When power can be saved with disk drives in a disk system then there are also potentials to save power consumed by power supplies. Because power supply controls the fan speed based upon the power consumption of the disk drives. If the disks save power then ultimately the power supplies can slow the fan down.

Problems solved by technology

If the disks save power then ultimately the power supplies can slow the fan down.

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