Log-structured Flash Storage Manager for Random Write Optimization

The patent introduces a Log-structured Storage Manager (LFSM) as an intermediary layer between the file system and the flash disk. This mediator converts random write requests into sequential writes by maintaining a log structure, thereby resolving the contradiction between coarse mapping granularity and random write performance. The LFSM acts as a buffer that translates random access patterns into sequential operations, eliminating the need for fine-grained mapping while preserving performance.

The patent changes the fundamental parameter of write operation sequencing from random to sequential. By implementing log-structured storage, the system transforms random write requests into sequential writes in the log, which then get mapped to physical flash locations. This parameter change from random to sequential writing eliminates the performance penalty associated with random writes on flash memory.

The patent implements continuous sequential writing to a log structure, eliminating the intermittent random write operations that trigger erasure and copying. The log-structured approach allows continuous appending of write operations in sequence, which is the most efficient operation for flash memory. This continuous sequential writing pattern eliminates the harmful erasure-and-copy cycle while maintaining simple write semantics.

The patent uses a log structure that copies write operations sequentially rather than directly modifying flash memory cells at random locations. The log acts as an intermediary buffer where writes are copied sequentially, and only when the log needs to be flushed are the operations translated to physical flash locations. This copying approach to sequential writes eliminates the need for repeated erasure and copying operations.

The LFSM serves as a mediator that accepts random access requests from the file system and translates them into sequential write operations. This intermediary layer maintains the adaptability to random access patterns while executing efficient sequential writes. The log structure allows the system to handle random access semantics without actually performing random physical writes, thus preserving both adaptability and performance.

The patent introduces an additional dimensional layer - the log structure - between the logical view (random access patterns) and the physical view (sequential writes). This extra dimension allows the system to maintain random access adaptability at the logical level while executing sequential operations at the physical level, resolving the contradiction between adaptability and performance.