SMR Hard Disk SCM Caching for Random Write Track Rewriting
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Solution Overview
Problem
SMR hard drives face severe performance degradation due to complex random write processes, which require extensive cache usage and can lead to cache exhaustion, especially in scenarios with frequent random writes, and existing solutions like DRAM caching introduce data loss risks and cost increases.
Innovation Solution
Implement a data buffering and integration method using Storage Class Memory (SCM) with real-time capacity monitoring, and when SCM capacity is exceeded, utilize a temporary memory cache area from the host device or a hard drive temporary cache area to manage random write operations, thereby expanding cache capacity and preventing overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DRAM caching is used to handle random writes, then write performance is improved, but data loss risk increases and cost increases
Solution Approach 1:
The patent uses SCM (Storage Class Memory) as a temporary cache for random write operations. SCM is non-volatile and cheaper than DRAM, providing sufficient cache capacity for the temporary data needed during track rewriting without requiring expensive DRAM. The SCM cache area serves as a disposable buffer that can be filled and emptied during write operations without risking data loss.
Solution Approach 2:
The patent creates a copy of the track data in the SCM cache area before performing the actual write operation on the platter. This copy mechanism allows the system to prepare and manage data temporarily in SCM, then transfer it to the platter, avoiding the need for volatile DRAM caching and its associated data loss risks.
2Productivity
If DRAM caching is used to handle random writes, then write performance is improved, but cost increases
Solution Approach 1:
The patent replaces expensive DRAM with cheaper SCM (Storage Class Memory) for the caching function. SCM provides sufficient cache capacity at a lower cost, making the solution more economically viable while maintaining the performance benefits of caching during random write operations.
3Productivity
If cache capacity is increased to handle frequent random writes, then performance degradation is reduced, but device complexity increases
Solution Approach 1:
The patent uses the SCM cache area for multiple purposes: storing track data during rewriting, buffering random write operations, and managing cache capacity dynamically. This multi-functional approach reduces the need for separate dedicated cache structures and simplifies the overall system architecture while maintaining performance.
Solution Approach 2:
The patent implements dynamic cache capacity management by monitoring the occupied capacity of the SCM cache area and adjusting operations based on real-time availability. When cache capacity is sufficient, random writes are processed directly; when capacity is exceeded, the system switches to a different processing mode, providing adaptive performance without fixed complex cache structures.
Data Source
AI summary
The present application relates to a random write instruction processing method, an SMR hard disk, and a computer device, and is applied to a main controller in the SMR hard disk. The SMR hard disk further includes a storage class memory SCM and a disk. The method includes: in response to receiving a random write instruction and random write data sent by a host device, performing a data buffering operation and a data integration operation in the SCM; and when the disk is subjected to track rewriting, caching track rewriting temporary data to the SCM.