Thanumalayan Sankaranarayana Pillai

How file systems differ, why this affects application-level consistency, and what we can do about it 02-27-2015 @ 4:55 - 5:55

Thanumalayan Sankaranarayana Pillai — Thanumalayan is a sixth-year graduate student at the University of Wisconsin-Madison, working with Prof. Andrea C. Arpaci-Dusseau and Prof. Remzi H. Arpaci-Dusseau. His current research concerns storage systems, in particular maintaining application-level consistency across unexpected power failures. Before Wisconsin, Thanumalayan did his undergraduate at the College of Engineering, Guindy (Anna University, India), where he was advised by Prof. Ranjani Parthasarathi. His undergraduate research project also concerned storage, and studied whether computer architecture can be changed to effectively use Flash storage.

Many applications have consistency mechanisms that allow them to recover after a power failure or a system crash. Such mechanisms inherently depend on some behaviors of the underlying file system. These file system behaviors are often misunderstood, and more importantly, differ between file systems.

In our research, we studied six (single-node) Linux file systems, so as to understand their behavior. We also studied eleven widely-used applications (including key-value stores and virtualization software) to understand whether their consistency mechanisms were correct. The tool we developed for studying applications (named ALICE) finds crash vulnerabilities, i.e., places where an application's consistency mechanism depends on behaviors obeyed by only some file systems. We found 60 vulnerabilities in the applications, by assuming a file system that has particularly bad behavior (from the perspective of the applications); 30 of those vulnerabilities are exposed when assuming popular, widely-used file systems. We are now focusing our efforts on making application-level consistency work, without affecting performance, and without requiring an application programmer to change much of the existing code.

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