Multi-speed Data Storage with Media Cache for Write Precision
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Solution Overview
Problem
Higher rotational speeds in data storage devices introduce non-repeatable runout effects and vibration issues, which hinder precise data writing and increase system limitations, especially with shingled magnetic recording techniques, necessitating a solution to manage rotational speeds effectively.
Innovation Solution
A data storage device configuration that rotates data recording media at different speeds, using a media cache to write data during higher speeds and transferring it to main memory during lower speeds, allowing for improved writeability and read performance without penalizing host I/O operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the data recording medium is rotated at higher speeds to improve data transfer rates, then read performance is improved, but non-repeatable runout effects and vibration issues increase, hindering precise data writing
Solution Approach 1:
The patent divides the data storage system into two distinct operational modes: a first operational mode for write operations at lower rotational speeds to ensure precision, and a second operational mode for read operations at higher rotational speeds to maximize data transfer rates. This segmentation allows each operation type to occur under optimal conditions without the harmful effects of high-speed rotation during writing.
Solution Approach 2:
The system dynamically adjusts the rotational speed of the data recording medium based on the operation being performed. The control circuit switches between different rotational speeds (e.g., 5400 rpm for writes, 7200 rpm for reads) to optimize both precision and performance, making the system adaptive to different operational requirements.
2Productivity
If the data recording medium is rotated at higher speeds to reduce operational latencies, then data transfer rates are enhanced, but vibration issues and system limitations increase
Solution Approach 1:
The patent separates read and write operations into different operational modes with different rotational speed requirements. Write operations occur at lower speeds to minimize vibration, while read operations occur at higher speeds to maximize data transfer rates. This segmentation eliminates the conflict between speed and vibration.
Solution Approach 2:
The system employs periodic switching between different rotational speeds based on operation type. The control circuit alternates between low-speed write mode and high-speed read mode, creating a periodic pattern of operation that optimizes both productivity and minimizes harmful vibrations during sensitive operations.
3Loss of time
If data is written directly to main memory at higher rotational speeds, then write performance is improved, but non-repeatable runout effects increase, hindering precise data writing
Solution Approach 1:
The patent implements a write buffer that temporarily holds data before it is written to the main memory on the rotating medium. Data is prepared and staged in the buffer in advance, allowing the system to maintain higher overall throughput while writing to the rotating medium at the slower, more precise speed required for accurate positioning.
Solution Approach 2:
The write buffer acts as an intermediary between the host system and the rotating data medium. It decouples the high-speed data generation from the lower-speed precise writing process, allowing data to be transferred to the buffer quickly while being written to the medium at the optimal slower speed for precision.
Data Source
AI summary
Apparatus and method for managing data transfers in a data storage device with rotational media that can be rotated at different speeds. In some embodiments, a non-volatile main memory is formed on a rotatable medium accessed by a moveable data transducer. A media cache provides a non-volatile data storage area. A control circuit directs writes to the main memory as the medium is rotated at a first speed and directs reads from the main memory as the medium is rotated at a higher, second speed. Writes during the rotation of the medium at the second speed are directed to the media cache instead of to the main memory so that no data are written to the main memory at the second speed. The media cache may also be located on the medium or may be formed from solid-state semiconductor memory.