Nonvolatile Storage Controller State-Group Backup Under Power Loss
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Solution Overview
Problem
Storage devices are vulnerable to data loss due to sudden power-offs, and existing backup methods using auxiliary power supplies are inefficient for backing up multi-bit data during such events.
Innovation Solution
A storage device with a storage controller that performs pre-programming and re-programming operations, generates state group data, applies error correction decoding, and backs up this data using limited auxiliary power during sudden power-offs, minimizing data size increase by removing ECC parity during the read operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary power supply is used for data backup during sudden power-off, then data reliability is improved, but the limited energy causes incomplete backup and wasted energy
Solution Approach 1:
The backup process is segmented into two phases: pre-programming phase where state group data is generated and stored in buffer memory, and re-programming phase where actual backup occurs. This segmentation allows the system to prepare data for backup in advance using normal power, so that during sudden power-off, only the final backup operation needs to be completed using limited auxiliary power, significantly reducing energy consumption while ensuring data reliability
Solution Approach 2:
The state group data is generated and prepared in the buffer memory during the pre-programming operation before the actual backup is needed. This preliminary action ensures that when sudden power-off occurs, the data is already ready in the buffer and only needs to be transferred to the auxiliary power supply area, minimizing the energy required from the auxiliary power supply while guaranteeing complete backup
2Speed
If multi-bit data is programmed directly, then programming speed is improved, but data loss risk increases during sudden power-off
Solution Approach 1:
The programming process is divided into pre-programming and re-programming operations. During pre-programming, state group data is generated and stored in buffer memory using fast programming. During re-programming, the actual data is programmed using the state group data for verification. This segmentation maintains high programming speed while ensuring data safety through the two-stage verification process
Solution Approach 2:
The state group data serves as feedback information that verifies the correctness of the programmed multi-bit data. By comparing the originally generated state group data with the data read back after programming, the system can detect and correct errors, ensuring data safety while maintaining the speed benefits of multi-bit programming
3Reliability
If ECC parity is included in backup data, then error correction capability is improved, but data size increases consuming more auxiliary power
Solution Approach 1:
The ECC parity information is extracted and stored separately from the main data in the buffer memory during the pre-programming phase. During sudden power-off backup, only the essential data needs to be backed up, while the ECC parity can be regenerated from the original data. This extraction reduces the amount of data that needs to be backed up using limited auxiliary power, thereby reducing energy consumption while maintaining error correction capability
Data Source
AI summary
Example embodiments are directed to a method for programming a storage device including a nonvolatile memory device and a storage controller for storing multi-bit data, programming, by the storage controller, the multi-bit data into the nonvolatile memory device based on a pre-programming operation, reading state group data of the multi-bit data generated in the nonvolatile memory device based on a program result of the pre-programming operation, and performing, by the storage controller, error correction decoding on the state group data.