Kerrighed is a Single System Image operating system for clusters. Kerrighed offers the view of a unique SMP machine on top of a cluster of standard PCs. The goals of Kerrighed are high performance of applications, high availability of the cluster, efficient resources management, high customizability of the operating system and ease of use. Kerrighed is implemented as an extension to Linux 2.4.24 (a set of Linux modules and a small patch to the kernel). Port to kernel 2.6.x is planned for later this year.