Memory Sub-System Firmware Block Record Management
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Solution Overview
Problem
The device block record in memory sub-systems becomes full quickly, leading to increased latency in programming operations due to the inability to record wordline start voltages for new blocks, as entries are not released promptly, causing additional voltage increments for each page to determine correct start voltages.
Innovation Solution
A firmware block record is maintained by the memory sub-system controller to track the contents and changes of the device block record, allowing the controller to infer when to send commands to remove specified entries from the device block record, creating space for new wordline start voltage information, thereby improving latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device block record is used to store wordline start voltages for all blocks, then complete voltage information is maintained, but the record becomes full quickly causing increased latency
Solution Approach 1:
The patent segments the block record management into two parts: a limited device block record stored in the memory device and a firmware block record maintained by the controller. The device block record stores only recently used block entries, while the firmware block record tracks all blocks. This segmentation allows the device block record to remain small and fast while maintaining complete voltage information in the firmware block record.
Solution Approach 2:
The firmware block record acts as an intermediary between the controller and the device block record. It tracks the contents and changes of the device block record, allowing the controller to infer when to send commands to remove specified entries from the device block record, creating space for new wordline start voltage information without requiring the device block record to store all blocks permanently.
2Loss of information
If entries are retained in the device block record for historical blocks, then voltage information is preserved, but space is unavailable for new blocks increasing latency
Solution Approach 1:
The controller performs preliminary actions by tracking block closures in the firmware block record before the device block record needs space. When the controller determines that a block has been closed (all pages written), it proactively sends commands to remove the corresponding entry from the device block record, ensuring space is available before new blocks need to be programmed.
Solution Approach 2:
The firmware block record provides feedback to the controller about the state of blocks (open/closed status). The controller uses this feedback to determine when to remove entries from the device block record, creating a feedback loop that ensures space management is synchronized with actual block usage patterns.
3Loss of time
If the device block record capacity is increased to store more blocks, then latency is reduced, but device complexity and memory usage increase
Solution Approach 1:
The patent merges the functions of tracking all blocks and maintaining device block record into a coordinated system. The firmware block record (in controller) and device block record (in memory device) work together as a unified management system, where the firmware block record handles the tracking of all blocks while the device block record maintains only the active entries needed for rapid voltage retrieval.
Data Source
AI summary
A request to perform a program operation at a memory device is received. Whether a firmware block record is to be modified to correspond with a device block record is determined based on parameters associated with the program operation. The firmware block record tracks entries of the device block record. Responsive to determining that the firmware block record is to be modified, the firmware block record is modified to correspond with the device block record.