SSD Reliability

SSD are complex electronic systems prone to wear-out and failure mechanisms mainly related to their basic component: the Flash memory. The reliability of a Flash memory depends on many technological and architectural aspects, from the physical concepts on which the store paradigm is achieved to the interaction among cells, from possible new physical mechanisms arising as the technology scales down to the countermeasures adopted within the memory controller to face erroneous behaviors. The SSD reliability is here analyzed at different levels: from the basic physical mechanisms affecting the traditional floating-gate cells and the possibility of anomalous erratic behavior, up to the disturbs arising because several cells share the same control lines. The solutions adopted to improve system reliability are presented, such as the use of RAID or the protection against power loss during write operations. Finally, test methods for endurance and retention verification will be described.