Adaptive Shingle Guard Band Width for SMR Drives
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shingled magnetic recording (SMR) drives use a uniform guard band width for all zones, which can be wider than necessary, leading to reduced formatting efficiency and data corruption due to overlapping tracks, as the magnetic erase width (MEW) varies across different zones.
Innovation Solution
Adaptive shingle guard band width adjustment based on the magnetic erase width (MEW) and shingle track pitch (STP) for each zone, dynamically calculating or using lookup tables to set the guard band width to minimize unused space while maintaining data integrity, such as setting it to 1×STP, 2×STP, or 3×STP depending on the MEW ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform guard band width is used for all zones in SMR drives, then data corruption is prevented, but format efficiency is reduced due to excessive unused space
Solution Approach 1:
The patent applies local quality by setting different guard band widths for different zones based on their specific MEW and STP characteristics. Each zone is analyzed individually and assigned an appropriate guard band width (1×STP, 2×STP, or 3×STP) rather than using a uniform width across all zones, thereby optimizing space utilization while maintaining data integrity in each specific zone.
Solution Approach 2:
The patent changes the guard band width parameter dynamically based on the measured MEW and STP values for each zone. The system calculates the MEW/STP ratio and adjusts the guard band width accordingly (1×STP for ratio < 1.5, 2×STP for ratio 1.5-2.5, 3×STP for ratio > 2.5), transforming a static uniform parameter into a dynamic adaptive parameter that responds to actual physical characteristics.
2Reliability
If a larger guard band width is used to prevent data corruption, then data integrity is maintained, but storage density is reduced due to increased overhead
Solution Approach 1:
The patent applies local quality by setting different guard band widths for different zones based on their specific MEW and STP characteristics. Each zone is analyzed individually and assigned an appropriate guard band width (1×STP, 2×STP, or 3×STP) rather than using a uniform width across all zones, thereby optimizing space utilization while maintaining data integrity in each specific zone.
Solution Approach 2:
The patent applies partial action by providing guard bands only to the extent necessary for each zone. Instead of uniformly applying excessive guard band width to all zones, the system provides minimal adequate protection (1×STP for zones with MEW/STP < 1.5) and scales up only where needed, avoiding unnecessary overhead in zones that require less protection.
3Productivity
If adaptive guard band width adjustment is implemented based on MEW and STP, then format efficiency is improved, but device complexity increases due to additional measurement and calculation requirements
Solution Approach 1:
The patent applies preliminary action by performing MEW and STP measurements and guard band width calculations during the formatting stage before actual data storage. The system pre-determines the appropriate guard band width for each zone based on measured characteristics, storing this information in a lookup table that guides subsequent data writing operations, thereby avoiding complex real-time calculations during normal operation.
Solution Approach 2:
The patent uses copying by creating a lookup table that stores the predetermined guard band width assignments for different zones. This table is generated during formatting based on MEW and STP measurements, and then copied/referenced during data writing operations, replacing the need for complex real-time calculations with simple table lookups.
Data Source
AI summary
Adaptively determining shingle guard band widths on at least one disk of a data storage device (DSD). The at least one disk includes a plurality of zones of shingle tracks for storing data. At least one of a magnetic erase width (MEW) and a magnetic read width (MRW) are measured and a shingle track pitch (STP) is determined. The shingle guard band width is determined based at least partly on the STP and at least one of the MEW or the MRW.