Shingled Band Cache Track for Random Write Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Shingled magnetic recording (SMR) data storage systems face challenges in writing random data, as it can corrupt subsequent tracks, requiring a different writing strategy and potentially detrimental to performance, especially when dealing with cache data that needs to be randomly written without mapping to host accessible logical block addresses (HLBAs).
Innovation Solution
Designating the last track of a shingled band as a randomly writable track that does not map to HLBAs, allowing it to overlap preceding tracks but not subsequent ones, and using a cache track that operates in drive accessible logical block address (DLBA) mode to manage and store cache data, enabling efficient data storage and retrieval without corrupting adjacent tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If random data is written to shingled tracks, then cache data can be stored, but subsequent tracks can be corrupted
Solution Approach 1:
The shingled band is segmented into multiple tracks with different access modes. The first track through second-to-last tracks are configured as sequential-write-only tracks for reliable data storage, while the last track is configured as a randomly readable and writable track for cache operations. This segmentation allows the system to simultaneously support both reliable sequential storage and flexible random access without mutual interference.
Solution Approach 2:
Different tracks within the shingled band are assigned different functional qualities: tracks 1 through N-1 have sequential-write-only properties to prevent corruption, while track N has random read/write properties for cache flexibility. This local differentiation of track properties enables each track to optimize for its specific purpose while maintaining overall system reliability.
2Ease of operation
If read-modify-write operations are performed on shingled tracks, then data can be updated, but performance is detrimental
Solution Approach 1:
The shingled band is divided into sequential-write-only tracks (1 through N-1) and a randomly readable and writable track (N). This segmentation allows the last track to serve as a cache where data can be randomly written without requiring read-modify-write operations, thereby maintaining high write performance while preserving data integrity on sequential tracks.
Solution Approach 2:
The last track acts as an intermediary cache between the host system and the sequential-write-only tracks. Data can be randomly written to this intermediary track without corruption risks, and when needed, it can be read back or flushed to the sequential tracks. This intermediary layer eliminates the need for performance-detrimental read-modify-write operations on the main data tracks.
3Quantity of substance
If the last track overlaps preceding tracks, then storage density increases, but writing to the last track risks corrupting preceding tracks
Solution Approach 1:
The shingled band is segmented into overlapping sequential-write-only tracks (1 through N-1) and a non-overlapping randomly readable and writable track (N). This segmentation allows the last track to be positioned such that it does not overlap with preceding tracks, eliminating the corruption risk while maintaining high storage density through the overlapping structure of tracks 1 through N-1.
4Ease of operation
If all tracks map to host accessible logical block addresses, then host access is simplified, but random writes can corrupt data
Solution Approach 1:
The shingled band is segmented into tracks that map to HLBAs (tracks 1 through N-1) and a last track that does not map to HLBAs. This segmentation allows the host to access data through HLBAs for reliable sequential tracks, while the last track serves as a protected cache area that cannot be directly accessed by the host, preventing accidental corruption while maintaining simple host access interfaces.
Solution Approach 2:
The last track functions as an intermediary buffer between the host and the HLA-mapped sequential tracks. Since it does not map to HLBAs, the host cannot directly write to it, providing automatic protection against corruption. The drive controller manages this intermediary track, allowing random writes for caching purposes while maintaining data protection and simple host access to the main data tracks through HLBAs.
Data Source
AI summary
A disc data storage medium can include a shingled band of tracks, some of which do not map to host accessible logical block address. The tracks that do not map to host accessible logical block addresses (cache tracks) can store cache data and may map to disc accessible logical block addresses. Data operations can be performed on the data in the cache tracks, and the data may then be moved to storage regions mapped to host logical block addresses.