QLC Data Programming Read Verify Overhead Reduction
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Solution Overview
Problem
Existing data storage devices, such as solid state drives (SSDs), face increased XOR parity overhead, which reduces capacity and reliability due to the accumulation of program failures during data programming.
Innovation Solution
Implementing a data storage device with a controller that performs read verify operations on a wordline or erase block basis to identify and fix program failures before programming to a second memory device, thereby reducing the need for XOR parity elements and enhancing storage capacity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If XOR parity data is generated and stored at each programming stage (foggy program, fine program, cache), then program failures can be corrected, but XOR parity overhead increases and storage capacity for user data decreases
Solution Approach 1:
The patent performs read verify operations after foggy programming to detect program failures before fine programming occurs. By identifying and correcting errors in advance, the system reduces the burden on XOR parity data, allowing smaller parity overhead while maintaining reliability. This preliminary detection action prevents error accumulation that would otherwise require extensive parity protection.
Solution Approach 2:
The patent dynamically adjusts the amount of XOR parity data stored based on the results of read verify operations. When program failures are detected and corrected early, the system reduces XOR parity overhead accordingly. This parameter adjustment optimizes the balance between reliability and storage capacity, allowing more user data to be stored when conditions permit.
2Reliability
If read verify operations are performed on every wordline and erase block, then program failures are detected early, but programming time and processing overhead increase
Solution Approach 1:
The patent applies read verify operations selectively to specific wordlines and erase blocks based on detected program failures, rather than uniformly to all data. When a program failure is detected in a particular location, read verify is applied to that specific area and related blocks, while other areas proceed with normal programming. This localized approach maintains reliability where needed while minimizing time loss in areas without issues.
Solution Approach 2:
The patent performs read verify operations on a partial basis initially, focusing on critical areas such as recently programmed wordlines and erase blocks. Rather than verifying every single wordline and block at full intensity, the system applies verification where most needed based on programming status and error detection, reducing overall processing time while maintaining adequate reliability coverage.
Data Source
AI summary
A data storage device includes one or more memory devices that each includes one or more superblocks and a controller coupled to the one or more memory devices. Each superblock includes a plurality of wordlines. The controller is configured to write data to a first wordline of the plurality of wordlines, write data to a second wordline of the plurality of wordlines, perform a read verify operation on the first wordline, and perform a read verify operation on the second wordline. At least one of the first wordline and the second wordline does not include an XOR parity element and one or more wordlines of the plurality of wordlines includes the XOR parity element.