Faster checkpointing with N+1 parity

This paper presents a way to perform fast incremental checkpointing of multicomputers and distributed systems by using N+1 parity. A basic algorithm is described that uses two extra processors for checkpointing and enables the system to tolerate any single processor failure. The algorithm´s speed comes from a combination of N+1 parity, extra physical memory, and virtual memory hardware so that checkpoints need not be written to disk. This eliminates the most time-consuming portion of checkpointing. The algorithm requires each application processor to allocate a fixed amount of extra memory for checkpointing. This amount may be set statically by the programmer, and need not be equal to the site of the processor´s writable address space. This alleviates a major restriction of previous checkpointing algorithms using N+1 parity. Finally, we outline how to extend our algorithm to tolerate any m processor failures with the addition of 2m extra checkpointing processors.<>