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 operating system (a set of Linux modules and a small patch to the kernel).
Kerrighed main features are :
Customizable Cluster Wide Process Scheduler. Processes and threads are automatically scheduled over the cluster nodes to balance the CPU load using the Kerrighed default scheduling algorithm. However, Kerrighed offers a toolkit to easily write customized schedulers hot-loadable through kernel modules.
High Performance Stream Migration Mechanism. Processes using streams (socket, pipe, fifo, char device, etc) can be migrated with no penalty on communication performance after migration.
Distributed File System.
A unique file name space is seen over the whole cluster. All cluster disks are merged in an unique virtual disk in a customizable RAID-like fashion.
Cluster Wide Unix Process Interface. All traditional UNIX process management commands (top, ps, kill, etc) operate cluster wide. Moreover, process identifiers (pid) are unique cluster wide.
Customizable Single System Image Features. Single system image features (shared memory, global scheduler, migrable streams, etc) can be enabled or disabled on a per process basis.