Multiple Disk Stacks on Rotatable Carousel HDD
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Solution Overview
Problem
The cost per unit of storage in hard disk drives (HDDs) remains a significant challenge, especially in large data storage scenarios where high storage capacity is required but infrequently accessed, such as in archival and backup storage.
Innovation Solution
A hard disk drive design featuring multiple disk stacks mounted on a rotatable carousel, with a single or multiple head stack assemblies that access each disk stack asynchronously or simultaneously after being rotated to a fixed position, effectively reducing the cost per unit of storage by amortizing the cost of read/write heads and electronics over increased media capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple disk stacks are mounted on a carousel to increase storage capacity, then the storage capacity increases, but the device complexity increases
Solution Approach 1:
Multiple disk stacks are combined on a single rotatable carousel platform, allowing them to be serviced by shared head stack assemblies. This merging approach increases storage capacity while amortizing the complexity of access mechanisms across multiple stacks.
Solution Approach 2:
The head stack assemblies are designed to service multiple different disk stacks through the carousel rotation mechanism, making them universal access devices. This multi-functionality reduces the need for dedicated access mechanisms for each stack, managing complexity while scaling capacity.
2Quantity of substance
If a single head stack assembly is used to access multiple disk stacks, then the cost per unit of storage decreases, but the productivity decreases
Solution Approach 1:
The system dynamically switches between different disk stacks by rotating the carousel to position the desired stack in the access position. This dynamic reconfiguration allows a single HSA to service multiple stacks, reducing cost while maintaining access capability through time-multiplexed operations.
Solution Approach 2:
The carousel rotates periodically to bring different disk stacks into position for access by the head stack assembly. This periodic rotation enables sequential access to multiple stacks, allowing cost reduction through shared hardware while maintaining productivity through structured time-multiplexed access patterns.
3Productivity
If multiple head stack assemblies are configured to access multiple disk stacks simultaneously, then the productivity increases, but the device complexity increases
Solution Approach 1:
Multiple head stack assemblies are combined with the carousel system to enable parallel access to multiple disk stacks. This merging of multiple HSAs with the rotational positioning mechanism achieves simultaneous productivity improvement while sharing the complexity of the carousel control system across multiple access channels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a lower cost per unit of storage by efficiently accessing multiple disk stacks with a single or multiple head stack assemblies, thereby reducing the overall cost of storage while maintaining high storage capacity.
Implementation Method 1
multiple disk stacks mounted on a rotatable carousel, with a single or multiple head stack assemblies that access each disk stack asynchronously or simultaneously after being rotated to a fixed position
Implementation Method 2
Write heads make use of the electricity flowing through a coil, which produces a magnetic field. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
Implementation Method 3
A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk
Data Source
AI summary
A lower cost per unit of storage hard disk drive (HDD) includes multiple disk stacks fixed to a carousel, and at least one head stack assembly (HSA) for accessing portions of the magnetic-recording disk(s) of each of the multiple disk stacks after the carousel rotates to move a disk stack in a fixed position relative to the HSA.