Computer Science Speaking Skills Talk

Wednesday, October 26, 2022 - 12:00pm to 1:00pm


Virtual Presentation - ET Remote Access - Zoom


THOMAS KIM, Ph.D. StudentComputer Science DepartmentCarnegie Mellon Univeresity

Reliability and Availability for Arrays of Zoned Namespace SSDs

For decades, the traditional block interface has been the standard for block storage devices, allowing random read and write access on sector granularity. While this perfectly matched the physical behavior of spinning magnetic drives, it proved a poor fit for flash-based solid state drives (SSDs) due to the inability to overwrite individual sectors on flash. This poor fit results in potentially severe and uncontrollable performance fluctuations when the SSD firmware performs garbage collection to facilitate the illusion of sector-granularity overwrites. The Zoned Namespace (ZNS) interface is a recently-introduced alternative to the traditional block interface, designed to more closely match the characteristics of flash memory and enable higher performance and lower cost for SSDs. These benefits do not come free, however, as software must be redesigned to use ZNS devices. This talk is split into two parts; first, an overview of the ZNS interface and other similar systems, followed by a discussion of our work designing and implementing RAID-like reliability and availability for arrays of ZNS SSDs. While conventional software RAID experiences up to an 87% drop in throughput when the underlying SSDs start performing garbage collection, our system, RAIZN, is unaffected by this problem. Presented in Partial Fulfillment of the CSD Speaking Skills Requirement.

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