Flash Memory Controller Deduplication via Signature Tables
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Solution Overview
Problem
Non-volatile data storage devices, such as flash memory devices, face inefficiencies and resource wastage due to the storage of duplicate data, which affects performance and resource utilization.
Innovation Solution
A controller in the data storage device generates and maintains a signature table and a logical mapping table to identify and manage duplicate data items by generating signatures for data items and comparing them to existing entries, updating the tables instead of rewriting duplicate data, thus conserving resources and reducing unnecessary writes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If duplicate data is stored in flash memory, then data storage capacity is increased, but memory resources are wasted and performance is degraded
Solution Approach 1:
The patent uses signature tables to create a reference copy of data characteristics rather than storing actual duplicate data. When duplicate data is detected through signature matching, only the signature table is updated with a pointer to the original data location, avoiding physical duplication of data blocks in flash memory.
Solution Approach 2:
The signature table acts as an intermediary layer between the host system and the flash memory. It mediates write operations by checking for duplicates before data is written, using signature comparison as a filtering mechanism to prevent unnecessary data storage and resource consumption.
2Quantity of substance
If duplicate data is written to flash memory, then data storage density is increased, but the endurance of the storage device is reduced due to unnecessary write and erase cycles
Solution Approach 1:
The system performs preliminary signature checking in the signature table before actual data is written to flash memory. This preliminary action identifies duplicate data and prevents unnecessary write cycles to the flash memory, thereby preserving device endurance while maintaining storage density.
Solution Approach 2:
Instead of copying actual data blocks for duplicates, the system creates lightweight signature entries that reference the original data. This copying approach maintains the appearance of multiple data versions while physically storing only one copy, reducing write/erase cycles and extending flash memory life.
3Loss of energy
If a signature table is implemented to detect duplicates, then resource waste from duplicate storage is reduced, but the complexity of the data storage system increases
Solution Approach 1:
The patent transforms the data representation by changing from storing actual data blocks to storing compact signature values (hashes or checksums) in the signature table. This parameter change reduces the memory footprint of the deduplication structure and simplifies comparison operations while maintaining effective duplicate detection.
4Loss of energy
If the signature table and logical mapping table are updated for duplicate detection, then unnecessary writes are minimized, but the processing time for write operations is increased
Solution Approach 1:
The system creates simplified signature representations of data that can be quickly compared in the signature table. This copying approach uses compact data structures (hash values or checksums) that require minimal processing time for comparison, reducing the time overhead of duplicate detection while preventing unnecessary writes.
Data Source
AI summary
A data storage device includes a memory and a controller. A method may be performed at the data storage device. The method includes receiving a request to write data, generating a signature of the data, and searching a signature table to determine if the generated signature is in the signature table. The signature table includes at least one signature table entry that includes a signature of stored data and a physical address of the stored data.