Trim Command Scheduling for Flash Memory Longevity
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Solution Overview
Problem
The frequent execution of trim commands on nonvolatile semiconductor storage devices in image forming apparatuses shortens their service life due to the upper limit on rewrite counts of storage elements, which reduces the longevity of flash memory.
Innovation Solution
The image forming apparatus is configured to reduce the execution count of trim commands by not executing them during file operations performed in power-saving mode, and instead executes trim commands when switching from normal to power-saving mode or during shutdown processes, thereby minimizing the wear on storage elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If trim commands are executed frequently on the nonvolatile semiconductor storage device to maintain storage performance, then storage performance is improved, but the service life of the flash memory is shortened due to the upper limit on rewrite counts
Solution Approach 1:
The patent implements periodic action by executing trim commands only at specific intervals (when switching from normal to power-saving mode or during shutdown) rather than continuously after every file operation. This periodic execution maintains storage performance while significantly reducing the total number of trim commands issued to the flash memory, thereby extending its service life.
Solution Approach 2:
The patent applies preliminary action by performing trim operations at predetermined moments (mode transitions or shutdown) before the storage device enters a low-power state or is turned off. This timing strategy ensures that trim commands are executed when the system is still operational and can manage the storage device properly, while avoiding unnecessary trim operations during power-saving modes when the storage device is less actively used.
2Reliability
If trim commands are executed after every file operation to ensure optimal storage performance, then storage performance is maintained, but the rewrite count of storage elements increases, reducing flash memory longevity
Solution Approach 1:
The patent extracts the trim command execution from the frequent file operation cycle and separates it into distinct, less frequent execution points (mode transitions and shutdown). This extraction removes the harmful effect of excessive trim commands on storage element wear while preserving the necessary trim operations for maintaining storage performance reliability.
Solution Approach 2:
The patent changes the execution parameter of trim commands from 'after every file operation' to 'at specific system state transitions'. This parameter change reduces the frequency of trim operations from potentially hundreds per day to just a few times per day, significantly reducing wear on storage elements while maintaining adequate storage performance through periodic trimming.
Data Source
AI summary
An image forming apparatus includes a nonvolatile semiconductor storage device, a memory, and a processor. The processor is configured to exert control in such a manner that, when the nonvolatile semiconductor storage device is notified of deleted file data and a trim command is to be executed, even if an operation on file data stored in the nonvolatile semiconductor storage device is performed in the state in which the operation state of the image forming apparatus is set to the power-saving state, the trim command is not executed on the nonvolatile semiconductor storage device in accordance with the operation performed on file data.