Replication technique based on a functional and attribute grammar computation model

We present a replication technique based on FTAG computation model where instances of a replicated application are active on different group of processors called replicas. FTAG (Fault Tolerant Attribute Grammar) is a functional and attribute based model [15]. The developed replication technique implements 'active parallel replication', that is, all replicas are active and compute concurrently a different piece of the application parallel code. In our model replicas cooperate not only to detect and mask failures but also to perform parallel computation. The replication mechanisms are supported by FTAG run time system and are fully application-transparent. Different novel mechanisms for checkpointing and recovery are developed. Rollback is achieved only if the system experience multiple failures, otherwise forward recovery [9] is performed. The replication technique takes full advantage of parallel computation to reduce computation time.