Computer Science Department
School of Computer Science, Carnegie Mellon University
On Correlated Failures in Survivable Storage Systems
Mehmet Bakkaloglu, Jay J. Wylie, Chenxi Wang, Gregory R. Ganger
Keywords: Survivable storage systems, availability modeling,
storage nodes, correlated failures
The design of survivable storage systems involves inherent
trade-offs among properties such as performance, security,
and availability. A toolbox of simple and accurate models of
these properties allows a designer to make informed decisions.
This report focuses on availability modeling. We describe two
ways of extending the classic model of availability with a
single "correlation parameter" to accommodate correlated failures.
We evaluate the efficacy of the models by comparing their
results with real measurements. We also show the use of the models
as design decision tools: we analyze the effects of availability
and correlation on the ordering of data distribution schemes and
we investigate the placement of related files.