RAID protected external secondary memory

Abstract

A redundant array of solid state disk drives is provided among the storage devices controlled by a storage controller. The solid state disk drives may serve as a level 2 cache using standard multi-level cache management algorithms. The solid state disks may share a drive channel with other storage devices or may have a dedicated channel. Multiple solid state disk devices may also be provided to avoid single points of failure. With two solid state disks, the storage processor could maintain the cache data in both devices. If one device fails, the other could be used to maintain data services. With two or more devices, other Redundant Array of Independent Disks organizations may be used to improve data-to-metadata ratio while maintaining fault tolerance. Using these Redundant Array of Independent Disks techniques, the plurality of solid state disks may then be organized as a single level 2 cache volume that serves as a second level cache for a storage controller.

Dependencies are inferred from the claim text.