Memory Controller Unmap Handling via Write Cache Buffer
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Solution Overview
Problem
Current storage devices face challenges in efficiently processing unmap requests, which involve deleting address mapping information, leading to issues with data validity and storage management.
Innovation Solution
A memory controller with a write cache buffer is used to store unmap addresses and prestored unmap-pattern data, allowing for the output of unmap-pattern data in response to read requests, ensuring proper data handling and management during unmap operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If unmap requests are processed by deleting address mapping information, then storage management flexibility is improved, but data validity and retrieval reliability deteriorate
Solution Approach 1:
The patent creates a copy of unmap-pattern data in the write cache buffer that mimics actual write operations. When unmap requests are received, instead of simply deleting address mappings, the system stores unmap-pattern data (typically zeros or specific patterns) in the write cache buffer at the corresponding addresses. This copying approach maintains the appearance of valid data at those addresses, ensuring that read requests return consistent data while the address mapping can be updated for storage management purposes.
Solution Approach 2:
The patent performs preliminary action by pre-storing unmap-pattern data in the write cache buffer before actual unmap operations are executed. The write cache buffer is prepared in advance to handle unmap requests by having the pattern data ready, so when an unmap request arrives, the system can immediately store the pattern data without needing to perform complex deletion operations or risk data inconsistency during the transition.
2Productivity
If address mapping information is deleted to process unmap requests, then storage space reusability is improved, but processing complexity and potential errors increase
Solution Approach 1:
The patent merges the unmap request processing with the existing write cache buffer operations. Instead of creating a separate complex unmap processing mechanism, the system uses the already-present write cache buffer to handle both normal write operations and unmap operations uniformly. By storing unmap-pattern data in the same buffer structure used for writes, the system simplifies the overall processing architecture while enabling storage space reusability through address mapping updates.
3Reliability
If unmap-pattern data is stored in write cache buffer, then data integrity during unmap operations is improved, but buffer memory usage increases
Solution Approach 1:
The patent changes the parameter of the data stored in the write cache buffer by using predetermined unmap-pattern data (such as all zeros or specific validation patterns) instead of arbitrary data. This parameter change ensures that any data read from the buffer after an unmap operation contains known, valid patterns rather than potential garbage or inconsistent data, thereby maintaining data integrity while using the same buffer memory resources.
Data Source
AI summary
Provided herein may be a storage device and a method of operating the same. A method of operating a memory controller Included in a storage device for processing an unmap request may include receiving an unmap request for requesting deletion of address mapping information for an unmap address from a host, storing the unmap address and prestored unmap-pattern data in a random access memory (RAM), and outputting the unmap-pattern data to the host in response to a read request for the unmap address being inputted.