Intelligent Write Routine for Unaligned Sector Buffering
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Solution Overview
Problem
Data storage devices face performance degradation due to the incompatibility between new 1K physical sector sizes and legacy systems that still operate with 512 byte block sizes, leading to inefficient write times as they must align data transfers and manage file allocation tables based on 512 byte formats, resulting in increased write time and reduced performance in time-critical applications.
Innovation Solution
An intelligent write command routine that maintains the read buffer data and copies adjacent sector data to the write buffer to splice around write data, avoiding unnecessary disk access when logical and physical sectors are unaligned, and utilizing read look-ahead data to reduce write time by maintaining current data in the read buffer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the physical sector size is changed to 1K to increase data throughput, then the data transfer rate is improved, but the compatibility with legacy systems and the alignment of data transfers deteriorate
Solution Approach 1:
The patent segments the 1K physical sector into two 512-byte logical sectors, allowing legacy systems to write to the first sector while the second sector is prepared for future writes. This segmentation enables the system to maintain 1K sector throughput performance while being compatible with legacy 512-byte addressing systems.
Solution Approach 2:
The patent performs preliminary reads of adjacent sectors into the read buffer before write operations occur. When a write command arrives for an unaligned LBA, the necessary patch data is already available in the read buffer, eliminating the need for additional read operations and reducing write time.
2Speed
If data transfers are aligned to even LBAs for optimal performance, then the write speed is improved, but the flexibility in data transfer positioning deteriorates
Solution Approach 1:
The patent introduces a read buffer as an intermediary between the host and the disk. The read buffer stores pre-read sector data that can be used to construct aligned write operations. This intermediary allows the system to accept unaligned write requests from the host while internally constructing aligned write operations to the disk, maintaining both flexibility and speed.
Solution Approach 2:
The patent performs preliminary reads of sectors into the read buffer before write operations. When a write command requires data from a specific LBA, the data is already available in the read buffer from a previous read operation, eliminating the need for additional read-modify-write cycles and ensuring aligned writes for optimal performance.
3Reliability
If the read buffer is cleared and re-read for each write command to ensure data accuracy, then the data integrity is improved, but the write time increases
Solution Approach 1:
The patent performs preliminary reads of sectors into the read buffer before write operations occur. When a write command arrives, the necessary patch data is already available in the read buffer from previous read operations, eliminating the need for additional read-modify-write cycles and reducing write time while maintaining data integrity.
Solution Approach 2:
The patent copies data from the read buffer to the write buffer to construct the final write operation. Instead of re-reading from the disk, the system copies the necessary sector data that is already cached in the read buffer, significantly reducing the time required to prepare write operations while ensuring data accuracy.
Data Source
AI summary
An intelligent write command routine improves the operational efficiency of a data storage device (DSD) by avoiding media access of the disk when a logical block address (LBA) and the physical sector are unaligned, thus reducing write time. When a write command is received by the DSD from the host, the intelligent write command routine maintains the read data of the read buffer, instead of clearing the read buffer and performing a read of the target sector on the disk per standard protocol. The intelligent write command copies the necessary adjacent sector data from the read buffer as a data patch to the write buffer to splice around the write data received with the write command. Following each write command, the data written to the disk in the write buffer is copied to the read buffer. The read buffer is maintained with the most current data on the disk and does not need to be flushed unless the LBA of the write command is beyond the data ranges stored in the read buffer.