Investigating Power Outage Effects on Reliability of Solid-State Drives

Solid-State Drives (SSDs) are recently employed in enterprise servers and high-end storage systems in order to enhance performance of storage subsystem. Although employing high speed SSDs in the storage subsystems can significantly improve system performance, it comes with significant reliability threat for write operations upon power failures. In this paper, we present a comprehensive analysis investigating the impact of workload dependent parameters on the reliability of SSDs under power failure for variety of SSDs (from top manufacturers). To this end, we first develop a platform to perform two important features required for study: a) a realistic fault injection into the SSD in the computing systems and b) data loss detection mechanism on the SSD upon power failure. In the proposed physical fault injection platform, SSDs experience a real discharge phase of Power Supply Unit (PSU) that occurs during power failure in data centers which was neglected in previous studies. The impact of workload dependent parameters such as workload Working Set Size (WSS), request size, request type, access pattern, and sequence of accesses on the failure of SSDs is carefully studied in the presence of realistic power failures. Experimental results over thousands number of fault injections show that data loss occurs even after completion of the request (up to 700ms) where the failure rate is influenced by the type, size, access pattern, and sequence of IO accesses while other parameters such as workload WSS has no impact on the failure of SSDs.Comment: Design, Automation & Test in Europe Conference & Exhibition (DATE), 2018. IEEE, 201

A survey of data recovery on flash memory

In recent years, flash memory has become more widely used due to its advantages, such as fast data access, low power consumption, and high mobility. However, flash memory also has drawbacks that need to be overcome, such as erase-before-write, and the limitations of block deletion. In order to address this issue, the FTL (Flash Translation Layer) has been proposed with useful functionalities like address mapping, garbage collection, and wear-leveling. During the process of using, the data may be lost on power failure in the storage systems. In some systems, the data is very important. Thus recovery of data in the event of the system crash or a sudden power outage is of prime importance. This problem has attracted attention from researchers and many studies have been done. In this paper, we investigate previous studies on data recovery for flash memory from FTL processing solutions to PLR (Power Loss Recovery) solutions that have been proposed by authors in the conference proceeding, patents, or professional journals. This will provide a discussion of the proposed solutions to the data recovery in flash memory as well as an overview

Multi-purpose embedded communication gateway : system design and testbed implementation

Masteroppgave i Informasjons- og kommunikasjonsteknologi IKT590 Universitetet i Agder 2014This dissertation revolves around developing a multi-purpose embedded communication gateway. The gateway is equipped with multiple communication interfaces including Ethernet, Bluetooth, WiFi, Zigbee, LTE, and it can be configured and utilized for many purposes, such as a failover of an Ethernet cable via 4G in order to maintain the network connectivity. Raspberry Pi circuit board and the operating system Raspbian are selected as the hardware and the software platforms respectively. Different communication interfaces are coordinated by the Raspberry Pi and are configured via Linux scripts according to various use cases. Furthermore, a hardware watchdog is adopted to enhance the availability of system. In addition, the system is encapsulated into a box to increase its portability. The system is validated and evaluated through rigorous test-bed experiments. Experiment results indicate that the developed router works smoothly and reliably in environments with little electrical disturbances