RRO Compensation Data Management in HDD NAND Memory
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Solution Overview
Problem
The calibration of repeatable runout (RRO) compensation data in hard disk drives (HDDs) is a time-consuming and costly process, especially for XMR drives which require calibration for four types of tracks, and existing methods risk damaging TLC NAND memory due to limited write cycles during reprocessing.
Innovation Solution
The method involves temporarily storing RRO compensation data in a single-level cell (SLC) area of NAND memory, minimizing SLC usage by only requiring it for one head type, and then moving the sorted data to a triple-level cell (TLC) area, reducing the risk of TLC memory damage and optimizing storage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If RRO compensation data is stored directly in TLC NAND memory, then storage capacity is maximized, but the memory is damaged due to limited write cycles during reprocessing
Solution Approach 1:
The patent segments the storage process into two distinct phases: a temporary storage phase using SLC area during calibration, and a permanent storage phase using TLC area after sorting. This segmentation allows the system to leverage the write-endurance of SLC during repeated calibration operations while ultimately utilizing the high-capacity TLC for final storage, thus resolving the contradiction between storage capacity and memory durability.
Solution Approach 2:
The patent applies preliminary action by first sorting and finalizing the RRO compensation data in the SLC area before transferring it to TLC. This preliminary processing in SLC protects the TLC memory from wear during the calibration process, as SLC's higher write endurance absorbs the reprocessing operations. Only after the data is finalized and sorted does the system perform the transfer to TLC, ensuring TLC is not subjected to damaging write cycles.
2Manufacturing precision
If RRO calibration is performed for all head types simultaneously, then calibration completeness is improved, but SLC space consumption increases
Solution Approach 1:
The patent segments the calibration process by head type, processing one head type at a time in the SLC area before moving to the next. This segmentation allows the system to maintain calibration completeness for all four head types while minimizing SLC space consumption at any given moment, as only the data for the current head type occupies SLC resources during processing.
Solution Approach 2:
The patent applies preliminary action by completing the entire calibration process for one head type and sorting its data into SLC before beginning calibration for the next head type. This sequential preliminary processing ensures that SLC space is efficiently utilized for one head type at a time, preventing space exhaustion while maintaining complete calibration coverage across all head types.
Data Source
AI summary
Processing hard disk drive (HDD) data track repeatable runout (RRO) compensation data includes, for each read-write head constituent to the HDD, and for each data track on which the read-write head operates, saving RRO compensation data to single-level cell (SLC) area of a NAND memory component, and finalizing the RRO data before processing the next read-write head of the HDD, thereby minimizing the SLC area used. Finalizing the RRO data may include sorting the RRO data for the read-write head in the SLC area, moving the sorted RRO data from the SLC area to triple-level cell (TLC) or other higher-level cell area of the NAND, and then erasing the RRO data from the SLC area to free up that memory space, thereby reducing the risk of wearing out the TLC area.