1. <architecture> Multiple servers providing the same service. The term may imply resilience to failure and/or some kind of load balancing between the servers. Compare RAIS.

2. <file system> An elementary unit of allocation of a disk made up of one or more physical blocks.

A file is made up of a whole number of possibly non-contiguous clusters. The cluster size is a tradeoff between space efficiency (the bigger is the cluster, the bigger is on the average the wasted space at the end of each file) and the length of the FAT.