Endurance Translation Layer (ETL) and Diversion of Temp Files for Reduced Flash Wear of a Super-Endurance Solid-State Drive

摘要

A flash drive has increased endurance and longevity by reducing writes to flash. An Endurance Translation Layer (ETL) is created in a DRAM buffer and provides temporary storage to reduce flash wear. A Smart Storage Switch (SSS) controller assigns data-type bits when categorizing host accesses as paging files used by memory management, temporary files, File Allocation Table (FAT) and File Descriptor Block (FDB) entries, and user data files, using address ranges and file extensions read from FAT. Paging files and temporary files are never written to flash. Partial-page data is packed and sector mapped by sub-sector mapping tables that are pointed to by a unified mapping table that stores the data-type bits and pointers to data or tables in DRAM. Partial sectors are packed together to reduce DRAM usage and flash wear. A spare/swap area in DRAM reduces flash wear. Reference voltages are adjusted when error correction fails.

主权项

1. An Endurance Translation Layer (ETL) method to increase endurance of a flash memory that has a low specified erase-cycle lifetime comprising:
creating an ETL in a dynamic-random-access memory (DRAM) buffer that is controlled by a controller and using the ETL to provide temporary storage to reduce flash wear; creating a spare/swap area in the DRAM buffer; operating a controller to use the spare/swap area in the DRAM buffer to merge valid data in a flash memory with new data to generate combined data; and writing the combined data to the flash memory; whereby a spare/swap function is performed by the controller using the DRAM buffer rather than the flash memory.