Idit Keidar and
In the 1995 ACM-SIGACT-SIGMOD-SIGART Symposium on Principles of
Database Systems (PODS), May 1995, pages 245--254.
The full version of this paper will appear in the Journal of Computer
and System Sciences (JCSS) special issue with selected papers from
PODS 1995. Please see: full paper.
This paper presents a new atomic commitment protocol, Enhanced Three
Phase Commit} (E3PC), that always allows a quorum in the system to
make progress. Previously suggested quorum-based protocols (e.g the
quorum-based Three Phase Commit (3PC)) allow a quorum to make progress
in case of one failure. If failures cascade, however, and the quorum
in the system is ``lost'' (i.e. at a given time no quorum component
exists, e.g. because of a total crash), a quorum can later become
connected and still remain blocked. With our protocol, a connected
quorum never blocks. E3PC is based on the quorum-based 3PC, and it
does not require more time or communication than 3PC. The principles
demonstrated in this paper can be used to increase the resilience of a
variety of distributed services, e.g. replicated database systems, by
ensuring that a quorum will always be able to make progress.
Last modified: Mon Jul 1 14:35:39 EDT 2002