Dynamic Head Depopulation in Mapped Storage Devices
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Solution Overview
Problem
Current disk drives lack the ability to migrate data from a failing head or surface to another, resulting in data loss when a head fails, as they cannot dynamically redirect access to alternate physical blocks without disrupting the logical block address mapping.
Innovation Solution
Implementing a dynamically mapped storage device that detects failing heads and migrates data on-the-fly to other physical locations, adjusting the mapping table to maintain data accessibility and integrity, while prioritizing critical data and avoiding weak subsections during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a head fails in a traditional disk drive, then data loss occurs, but implementing dynamic head depopulation requires complex mapping table adjustments and data migration mechanisms
Solution Approach 1:
The patent implements dynamic head depopulation by making the mapping table adjustable and relocatable. When a head fails, the system dynamically updates the mapping table to redirect logical block addresses from the failed head to alternative healthy physical blocks on other surfaces, enabling the system to adapt to failure conditions in real-time without manual intervention
Solution Approach 2:
The system changes the mapping parameters (logical-to-physical block mappings) dynamically based on head health status. By modifying the mapping table entries to point to alternative physical locations when a head fails, the system transforms the static mapping structure into a flexible parameter set that can be adjusted to maintain data accessibility despite hardware failures
2Ease of operation
If data is migrated from a failing head to another surface, then data accessibility is maintained, but storage capacity is reduced due to avoiding weak subsections
Solution Approach 1:
The system performs preliminary identification of weak subsections and failing heads during manufacturing and operation. By pre-mapping logical blocks to avoid known weak areas and proactively migrating data before complete failure occurs, the system ensures data accessibility is maintained while minimizing the impact on usable storage capacity
3Reliability
If the mapping table is adjusted to redirect access from a failed head, then data integrity is maintained, but access time increases due to data migration
Solution Approach 1:
The system creates alternative mappings in the mapping table that point to copy locations of data on healthy surfaces. When a head fails, the mapping table is adjusted to use these pre-identified alternative physical blocks, allowing data access to continue through the copied locations without requiring time-consuming data transfer operations during failure events
Data Source
AI summary
Methods and structures for providing on-the-fly head depopulation in a dynamically mapped storage device. In a dynamically mapped storage device in which all user supplied logical blocks are dynamically mapped by the storage device controller to physical disk blocks, features and aspects hereof allow on-the-fly head depopulation to protect data when a subsection of a storage device, such as a head of surface is failing. When the storage device detects that a head is failing, data may be migrated off the failing subsection into other subsections (e.g., a different head or surface) using mapping features and aspects hereof. Thus, the data on the failing subsection is still available should the subsection or head eventually fail.