Log-Based Directory Resolution in the Coda File System
Puneet Kumar, M. Satyanarayanan
Optimistic replication is an important technique for achieving high availability
in distributed file systems. A key problem in optimistic replication is
using semantic knowledge of objects to resolve concurrent updates from
multiple partitions. In this paper, we describe how the Coda File System
resolves partitioned updates to directories. The central result of our
work is that logging of updates is a simple yet efficient and powerful
technique for directory resolution in Unix file systems. Measurements from
our implementation show that the time for resolution is typically less
than 10% of the time for performing the original set of partitioned updates.
Analysis based on file traces from our environment indicate that a log
size of 2 MB per hour of partition should be ample for typical servers.