leff@CSVAX.SEAS.SMU.EDU (Laurence Leff) (07/22/90)
Please order this as indicated below. Do not reply to the moderator (me) or post something. The following technical report is available via anonymous FTP from midgard.ucsc.edu (128.114.134.15). It is in pub/tr/ucsc-crl-90-35.ps.Z -- so be sure to use binary mode transfer. A paper copy of this report is also available. Write to: Jean McKnight Technical Librarian Baskin Center for Computer Engineering & Information Sciences University of California Santa Cruz, CA 95064 Internet: jean@cis.ucsc.edu Protecting Replicated Objects Against Media Failures Jehan-Francois Paris Department of Computer Science University of Houston Houston, TX 77204-3475 Darrell D.E. Long Computer and Information Sciences University of California Santa Cruz, CA 95064 ABSTRACT We present a replication control protocol that provides excellent data availabilities while guaranteeing that all writes to the object are recorded in at least two replicas. The protocol, robust dynamic voting (RDV) accepts reads and writes as long as at least two replicas remain available. The replicated object remains inacces- sible until either the two last available replicas recover or one of the two last available replicas can collect the votes of a majority of replicas. We evaluate the read and write availabilities of replicated data objects managed by the RDV pro- tocol and compare them with those of replicated objects managed by majority consensus voting, dynamic voting and hybrid dynamic voting proto- cols. We show that RDV can provide extra protec- tion against media failures with no siginificant loss of availability.