Band Rewrite Optimization for SMR Drives
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Solution Overview
Problem
Disc drives face performance issues due to high-latency and defective sectors, which cause delays, fragmentation, and increased seek times, leading to slower access times and lower throughput.
Innovation Solution
A method is introduced to compare high-latency data sectors with target sectors to determine which can be skipped during data retrieval, using a skip mask to optimize the band updating process by reducing redundant disc revolutions and retries, thereby improving performance and hardware lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all sectors are read during band updating, then data integrity is ensured, but access time increases and throughput decreases due to high-latency and defective sectors
Solution Approach 1:
The system performs preliminary identification of high-latency and defective sectors before the band updating operation. By pre-marking these sectors in a skip mask, the system prepares in advance to avoid them during data retrieval, thus reducing access time without compromising data integrity for valid sectors
Solution Approach 2:
The system implements a skip mask mechanism that allows the data retrieval process to skip over identified high-latency and defective sectors. This enables the read head to bypass problematic areas quickly, reducing wasted time on sectors that would cause delays or require retries, while still ensuring complete retrieval of valid data sectors
2Reliability
If redundant disc revolutions are performed to retrieve data, then complete data retrieval is achieved, but mechanical wear increases and power consumption rises
Solution Approach 1:
The system pre-identifies defective and high-latency sectors and creates a skip mask before the band updating operation begins. This preliminary action allows the system to plan the data retrieval path in advance, avoiding sectors that would require multiple revolutions or retries, thus reducing mechanical wear and power consumption while ensuring complete retrieval of valid data
Solution Approach 2:
By implementing the skip mask mechanism, the system enables the data retrieval process to bypass problematic sectors entirely, reducing the number of disc revolutions needed. This skipping approach minimizes mechanical movement and energy consumption while maintaining complete data retrieval for all valid sectors
3Productivity
If high-latency sectors are accessed during band updating, then all data is retrieved, but command response time variance increases
Solution Approach 1:
The system performs preliminary identification and marking of high-latency sectors in the skip mask before the band updating operation. This advance preparation allows the data retrieval process to anticipate and bypass sectors that would cause variable delays, resulting in more consistent command response times while still retrieving all necessary valid data
Solution Approach 2:
The skip mask mechanism enables the system to skip over high-latency sectors during data retrieval, eliminating the variable delays that would otherwise occur when accessing these problematic sectors. This results in reduced command response time variance and more predictable performance, while ensuring complete retrieval of valid data sectors
Data Source
AI summary
Implementations disclosed herein provide a method comprising comparing high-latency data sectors of a storage band, the high-latency data sectors having latency above a predetermined threshold, with target sectors for storing new data to determine one or more of the high-latency data sectors that may be skipped during retrieval of at-rest data from the storage band.