Designing SSI clusters with hierarchical checkpointing and single I/O space

(SSI) in a workstation cluster. In a cluster of computers, local area networks or highbandwidth switch networks using optical fibers physically connect a collection of node computers. The workstations in a cluster can work collectively as an integrated computing resource—that is, an SSI—or they can operate as individual computers, separately. Present clusters are usually small and provide only limited SSI services. Future clusters will likely increase in scalability and offer more SSI support, as Figure 1 illustrates. The implication is that future clusters could replace the MPP, SMP, or CC-NUMA architectures (see “The cluster as a computer architecture” sidebar for key characteristics of these computer platforms). We focus on clusters with high availability through SSI support, distributed RAID (redundant arrays of inexpensive disks) with parity checks, and hierarchical checkpointing with adaptive recovery. In particular, we developed a single I/O address space among all disks and peripheral devices attached in the cluster. This enables direct remote disk access, which is a necessary step to implement a Adopting a new