SSD In-Process Read Consolidation to Reduce Die Collisions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Die collisions in solid-state drives (SSDs) lead to increased read command completion times due to busy resources, as multiple commands compete for access to the same flash memory dies and channels, resulting in reduced performance and efficiency.
Innovation Solution
Implementing an in-process read consolidation technique where the controller monitors for operationally proximate read commands and issues an expanded read command to retrieve an expanded set of data, including the initial and additional readback data, thereby reducing die collisions and enhancing client I/O performance by utilizing already allocated resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple read commands are issued to access flash memory dies, then data retrieval capability is improved, but die collisions occur causing increased completion times
Solution Approach 1:
The patent combines multiple in-process read commands into a single expanded read command when the commands are operationally proximate (targeting the same or overlapping dies/channels). This merging eliminates die collisions by consolidating resource usage, allowing the SSD to retrieve data for multiple commands in a single operation without the completion time penalty that would result from sequential execution or resource contention.
Solution Approach 2:
The controller performs preliminary evaluation of pending read commands to identify those that are operationally proximate before issuing commands to the flash memory. By pre-analyzing command targets and determining consolidation opportunities in advance, the system can proactively merge commands that would otherwise cause die collisions, thereby preventing time loss before it occurs.
2Reliability
If read commands are processed sequentially to avoid die collisions, then resource contention is reduced, but overall throughput decreases
Solution Approach 1:
The patent merges multiple read commands into a single expanded command that retrieves data for multiple logical block addresses in one operation. This approach maintains reliable resource allocation by targeting the same dies/channels efficiently while significantly improving throughput by eliminating the need for sequential command execution and avoiding die collisions that would reduce productivity.
Solution Approach 2:
By consolidating multiple read operations into a single continuous command execution, the system maintains uninterrupted useful action on the flash memory resources. The expanded read command keeps the dies and channels occupied productively throughout the entire data retrieval process, eliminating idle periods and resource switching that would occur with sequential processing, thereby improving both reliability and throughput.
3Productivity
If expanded read commands are issued to consolidate data retrieval, then die collisions are reduced, but command complexity increases
Solution Approach 1:
The patent merges multiple simple read commands into a single expanded read command with a more complex structure that includes multiple logical block address ranges. While the command structure itself becomes more complex, this consolidation reduces overall system complexity by eliminating the need for multiple separate command issuance, completion waiting, and resource management operations, thereby improving read operation efficiency despite the increased individual command complexity.
Data Source
AI summary
Method and apparatus for managing data in a storage device, such as a solid-state drive (SSD). In some embodiments, a first read command from a command queue is forwarded to a non-volatile memory (NVM) to request retrieval of a first set of readback data. While the NVM initiates in-process execution of the first read command, an expanded read command is issued to the NVM. The expanded read command supercedes the first read command and requests an expanded set of readback data that includes the first set of readback data as well as a second set of readback data. The second set of readback data may be associated with a second read command in the command queue. The NVM transfers the expanded set of readback data to a read buffer responsive to the expanded read command. The first and second read commands may be client reads, background reads or both.