Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism
Reexamination Certificate
2000-07-11
2003-09-30
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Reexamination Certificate
active
06628469
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electrically powered disk storage units and, in particular, to a low power consuming magnetic hard disk storage unit having multiple spindles and associated magnetic disks.
BACKGROUND OF THE INVENTION
A hard disk drive (HDD) unit typically comprises a spindle, at least one disk platter rotatably supported by the spindle, at least one read-write head for reading/writing information from and to the disk platter(s), actuators for accurately positioning the read-write head(s) relative the disk platter(s) and an electronic controller for controlling the operation of the HDD. Various innovations have led to dramatic increases in the storage capacity and performance of (HDD) units and the miniaturization to smaller form factors. The storage capacity of HDDs has grown rapidly, historically exhibiting growth rates of 50 to 60% per year while showing growth rates of 130% per year in recent years. Almost as dramatic is the continuing reduction of the average cost per megabyte accompanying the increasing HDD capacities. The increased storage capacities and lower prices of HDDs have helped spur the proliferation of applications and devices using HDDs. While the storage capacities and costs of HDDs have improved, HDDs remain relatively power hungry as compared to other computer hardware devices. Furthermore, the power consumption requirements of HDDs is increasingly becoming more of a concern as the applications and devices using HDDs grow, especially for portable and mobile devices that rely on limited power sources such as batteries.
Of all the components comprising the typical disk drive unit, powering the rotation of the disk unit's spindle is the single largest consumer of power. HDDs also require a greater amount of power during their startup since initiating the rotation of the magnetic disk platter(s) typically induces a current spike exceeding the normal operational power requirements of the HDD.
Attempts at reducing the -power consumption needs of a disk drive unit include reducing the size, particularly the diameter, of the magnetic disk platter(s). Less torque and power is typically required to initiate, maintain and stop the rotation of disk platter(s) having smaller diameters as compared to larger diameter disk platter(s). A disadvantage with decreasing the diameter of the disk platter(s) is that the readable/writeable surface area of disk platter(s) also decreases. While increases in areal density and decreases in recordable bit sizes continue to be researched and developed so that more data may be read-written onto smaller spaces, disk platter(s) having smaller diameters are capable of storing less data than similarly formatted larger diameter disk platter(s).
Another factor impacting the power consumption needs of a HDD is the rate of rotation for a spindle and the disk platter supported thereon. More power is generally required to rotate a disk faster than to rotate the same disk at a lower rate of speed. Currently, HDDs having rotation rates of 10,000 revolution per minute (rpm) are installed on desktop computers, and 5,000-7,000 rpm HDDs are used in laptop computers.
Therefore, more than continued miniaturization of HDD components is needed to achieve HDD power reductions while not sacrificing HDD performance or capacity.
It is known in the prior art to reduce the power consumption needs of a disk drive unit by reducing the diameter of the disk drive unit's magnetic disks and starting only one disk at startup. European Pat. No. 671,741, published Sep. 13, 1995 entitled “A Small Memory Unit With A Hard Disk”, discloses housing either two 1.3″, three 1.0″ or four 0.7″ diameter magnetic platters in the same housing originally intended for a single 1.8″ diameter magnetic disk platter. Activating only one disk at the time of starting the disk operation reduces power consumption.
It is further known to house several smaller disk drives in a housing originally intended for a larger disk drive device. Japanese Pat. No. 6-084338, published Mar. 25, 1994 entitled “Array Type Recording Device” discloses an array type configured disk storage device comprising multiple disk array units, each housed in standard sized 5.25″ enclosures for incorporating the array type disk array device in personal computers, etc. having standard 5.25″ computer expansion slots.
It is known to control the power consumption of a disk drive unit based on sequence control. Japanese Pat. No. 10-255451 published Sep. 25, 1998 entitled “Method for Supplying Power to Hard Disk” discloses a power supply having a control function for controlling the power supplied to a plurality of HDDs based on sequence control.
It is known to provide multiple disk spindles on a single baseplate. Japanese Pat. No. 5-325496 published May 26, 1994 entitled “Disk Device” discloses a disk storage device having two spindles on a single baseplate. The power consumption needs of the disk drive unit are reduced by an electric power control circuit that smoothes the power supply requirements of the disk drive unit.
SUMMARY OF THE INVENTION
The inventor has realized that a great majority of the information stored on hard disk drives, HDDs, is not frequently accessed for read-write purposes. Instead, only a relatively small percentage of a HDD is typically used to store the most frequently used data, such as commonly used operating system, data files, applications programs and modest data sets.
The present invention results from the further realization by the inventor that a low power consuming disk drive unit is effectuated by a disk drive unit having multiple HDDs and/or HDD subsystems of differing power consumption requirements and functioning as an integrated unit wherein only the more energy efficient HDD subsystem is selectively powered the majority of the disk drive unit's operating time. As used herein, a HDD subsystem typically comprises at least one spindle, at least one disk platter rotatably supported by the spindle, at least one read-write head for reading/writing information from and to the disk platter(s), actuators for accurately positioning the readwrite head(s) relative the disk platter(s) and associated electronics and electronic controller which may be shared with other HDD subsystem(s). The more efficient HDD subsystem has smaller diameter disk platter(s) than the less efficient HDD subsystem(s), although other factors may also influence the power efficiencies of the HDDs. The multiple HDDs of the present invention function as an integrated device. The combined total storage capacity of the multiple HDD subsystems is typically comparable to, if not greater than, a conventional disk drive unit. Accordingly, the disk drive unit of the present invention has lower power consumption requirements without sacrificing performance or storage capacity.
The low power consuming disk drive unit comprises multiple HDD subsystems having different power consumption needs. Each HDD subsystem typically comprises a spindle, at least one disk platter rotatably supported by the spindle, at least one read-write head for reading/writing information from and to the disk platter(s), actuators for accurately positioning the read-write head(s) relative the disk platter(s) and an electronic controller for controlling the operation of the HDD subsystem. The smaller/more efficient HDD subsystem comprising the disk drive unit is typically used to store the most commonly accessed data while the less efficient/larger HDD subsystem (s) stores the less frequently accessed information. Note that, as used throughout this document, accessing information on a HDD and/or HDD subsystem encompasses both reading and writing information on a HDD.
Although smaller, the more efficient HDD subsystem is sufficiently sized to store the frequently accessed information so that there is no compromise in the disk drive unit's performance. Since the smaller/more efficient HDD subsystem, stores the frequently used information, it is the smaller/more efficient HDD that i
Hudspeth David
International Business Machines - Corporation
Martin Robert
Ohlandt Greeley Ruggiero & Perle L.L.P.
Slavitt Mitchell
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