Certification-based database replication protocols are a good basis to develop replica recovery when they provide the snapshot isolation level. For such isolation level, no readset needs to be transferred between replicas nor checked in the certification phase. Additionally, these protocols need to maintain a historic list of writesets that is used for certifying the transactions that arrive to the commit phase. Such historic list can be used to transfer the missed state of a recovering replica. We study the performance of the basic recovery approach -to transfer all missed writesets-and a version-based optimization -to transfer the latest version of each missed item, compacting thus the writeset list-, and the results show that such optimization reduces a lot the recovery time.

Replication is used for providing highly available and fault-tolerant information systems, which are constructed on top of replication and recovery protocols. An important aspect when designing these systems is the assumed failure model. Replicated databases literature last trends consist in adopting the crash-recovery with partial amnesia failure model because in most cases it shortens the recovery times. But, despite the large use of such failure model we consider that most of these works do not handle accurately the amnesia phenomenon. Therefore, in this paper we survey some works, analyzing their amnesia support. In this study, we focus on primary component membership systems. The same principles could be applied for partitionable or mobile systems, but we have not surveyed them.

The main goal of replication is to increase dependability. Recovery protocols are a critical building block for realizing this goal. In this survey, we present an analysis of recovery protocols proposed in recent years. In particular, we relate these protocols to the replication protocols that use them, and discuss their main advantages and disadvantages. We classify replication and recovery protocols by several characteristics and point out interrelationships between them.