DATE: Monday, November 9, 2015
TIME: 3:00 pm - 4:00 pm
PLACE: RMCIC 4th Floor Panther Hollow Room

SPEAKER: George Amvrosiadis, University of Toronto

TITLE: Opportunistic Storage Maintenance

Storage systems rely on maintenance tasks, such as backup and layout optimization, to ensure data availability and good performance. These tasks access large amounts of data and can significantly impact foreground applications. The premise of this talk is that storage maintenance could be performed more efficiently by prioritizing processing of data that is currently cached in memory. Data can be cached either due to other maintenance tasks requesting it previously, or due to overlapping foreground I/O activity. I will be presenting Duet, a framework that provides notifications about page-level events to maintenance tasks, such as a page being added or modified in memory. Tasks use these events as hints to opportunistically process cached data. Our results show that tasks using Duet can complete maintenance work more efficiently because they perform fewer I/O operations. The I/O reduction depends on the amount of data overlap with other maintenance tasks and foreground applications. Consequently, Duet's efficiency increases with additional tasks because opportunities for synergy appear more often.

George is a Ph.D. Candidate and member of the Systems and Networks lab of the Computer Science Department at the University of Toronto. Under the supervision of Prof. Angela Demke Brown and Prof. Ashvin Goel, he is currently investigating ways to enable applications with a strong storage component to collaborate on overlapping work, allowing them to reach their goals faster. His earlier work focused on storage reliability (under the supervision of Prof. Bianca Schroeder), high-performance clustered file systems (at IBM Research), and using data analytics to uncover pain points in modern backup and recovery software (at Symantec Research Labs). He enjoys operating systems research, with a focus on storage, especially when rooted in insights from real-world data analysis.

VISITOR HOST: Garth Gibson
VISITOR COORDINATOR: Angela Miller,, 8-6645

Karen Lindenfelser, 86716, or visit