COLLOQUIUM
             Computer Science Department, Boston University

Speaker: Timothy E. Denehy
         The University of Wisconsin

Date:  Wednesday, March 22, 2006
Time:  11:00
Place: Room MCS 135, 111 Cummington Street 
       (for directions, see www.cs.bu.edu/colloquium)

Title: Information and Collaboration in the Storage Stack

Abstract:

For over two decades, the interface between file systems and storage
systems has consisted of a simple, linear array of blocks that can be
read and written.
This abstraction has enabled innovations in each of the surrounding
layers, but it also obscures implementation details that may compromise
the performance and reliability of the system as a whole.  In this talk
I will discuss two pieces of work that address this limitation in the
storage interface.

First, I will describe Shear, a software system that automatically
discovers the important RAID properties hidden by the block interface.
This information can be used to improve performance by tuning the file
system to particular RAID characteristics.  Shear can also be used in a
management context to verify RAID construction and monitor the operation
of an array.  Second, I will describe journal-guided resynchronization,
which uses file system knowledge and an expanded interface to improve
the process of software RAID crash recovery.
This collaborative approach reduces recovery time by several orders of
magnitude, improving reliability and availability while suffering little
performance loss during normal operation.

Host: Rich West