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

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.