William Jannen

Position: Associate Professor
Pronouns: he/him
Phone: 413-597-4509
Office: TPL 304
E-mail: [email protected]


  • Ph.D. Stony Brook University, 2017
  • B.A. Williams College, 2009


  • Design and analysis of file systems
  • Media-specific optimizations for storage
  • Data structures
  • Write optimization


Bill received his PhD from Stony Brook University where his research focused on file systems and storage. He is part of the team that made BetrFS, a Linux file system built using write-optimized dictionaries.


Bill is involved in ongoing projects at all levels of the storage stack. At the block layer, he is working on a software translation layer for host-managed shingled magnetic recording drives. At the file system layer, he is working to improve, stabilize, and measure the BetrFS file system. At the application layer, he is exploring new query models that bring to reads the same benefits that write-optimization brings to writes.