Today, there are two primary RAID (Redundant Array of Independent Disks) architectures for maintaining the location of “write journal” information. Older generation RAID subsystems maintain the write journal in battery-backed external SDRAM memory. Because of its importance for fast writes and long retention under power interruption scenarios, newer
generation RAID subsystems implement write journaling in separate nvSRAM (non-volatile SRAM) devices. This white paper discusses the merits of implementing write journaling using Simtek nvSRAM.