Non-Volatile Cache for Shingled Magnetic Recording Data Updates
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Solution Overview
Problem
Existing data storage systems using shingled recording in hard disk drives face challenges in efficiently updating data within overlapping tracks, as overwriting one track erases data in subsequent tracks, requiring sequential recording to prevent data loss, and lack a reliable method for storing updated data during the process.
Innovation Solution
Incorporating a non-volatile cache memory circuit to store shingle blocks of data from overlapping tracks, allowing for updating of data in these blocks while maintaining data integrity by storing updated information in a semiconductor solid-state memory, such as Flash or EEPROM, which can retain data during power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential recording is used to update data in overlapping tracks, then data integrity is maintained, but storage efficiency and productivity are reduced
Solution Approach 1:
A non-volatile cache memory circuit is introduced as an intermediary component between the host system and the shingled magnetic recording medium. The cache stores shingle blocks during update operations, allowing the system to temporarily hold data blocks while performing selective updates without requiring sequential access patterns. This mediator enables parallel processing of multiple tracks simultaneously while maintaining data integrity through the cache's non-volatile nature.
2Reliability
If non-volatile cache memory is used to store shingle blocks, then data integrity during updates is improved, but device complexity increases
Solution Approach 1:
The non-volatile cache memory circuit serves multiple functions within the data storage system: it acts as a buffer for incoming data, a temporary storage for shingle blocks during update operations, and a protection mechanism against power failures. By consolidating these multiple functions into a single component, the overall device complexity is managed more efficiently than if separate components were used for each function.
3Productivity
If shingle blocks are stored in non-volatile cache during updates, then productivity is improved, but loss of information risk increases during power failure
Solution Approach 1:
The non-volatile cache memory provides beforehand cushioning by continuously holding shingle blocks in a safe, non-volatile state during update operations. This cushioning effect ensures that even if power is lost during an update, the data in the cache is not corrupted because non-volatile memory retains data without power. The cache acts as a protective buffer that prevents data loss scenarios that would occur with volatile memory.
Data Source
AI summary
A data storage apparatus includes a data storage medium, a write element, a non-volatile cache memory circuit, and a controller circuit. The controller circuit is configured to record data on the data storage medium in groups of overlapping tracks using the write element. The controller circuit is configured to store a shingle block of data from a subset of the overlapping tracks in the non-volatile cache memory circuit, while at least a portion of the data in the shingle block of data is updated.