[2][3] OpenSSI is based on the Linux operating system and was released as an open source project by Compaq in 2001.

The implementation of the single process space is accomplished using the VPROC abstraction invented by Locus for the OSF/1 AD operating system.

When running processes are migrated they continue to have access to any open files, IPC objects or network connections.

OpenSSI uses the context dependent symbolic link (CDSL) feature, inspired by HP's TruCluster system, to allow access to node-specific files in a manner transparent to non cluster-aware applications.

CFS is stacked on top of the real file system and co-ordinates access from different nodes using a token mechanism.

One node has physical access to the underlying file system and performs all read and write operations.

CFS can be used in a fault tolerant system by using shared disk subsystems (dual ported SCSI or SAN), or by using DRBD.

OpenSSI provides internode access to all the standard Linux inter-process communication mechanisms, shared memory, semaphores, SYSV message queues, pipes and Unix domain sockets.

[6] The origins of OpenSSI date back to the early 1980s, when the LOCUS distributed operating system was developed at UCLA.

The group that created ″LOCUS″ went on to form the Locus Computing Corporation in 1982, and produced versions of the technology derived from it under several names.

In the mid-1990s, this work culminated in the UnixWare NonStop Clusters product at Tandem Computers, which by 1995 took over the team of the former Locus CC and rights to the technology.

When SCO Group stopped selling the product, the developers (brought in by the Tandem acquisition and now working at Compaq) ported the ″NonStop Clusters″ code to Linux and in 2001, now called OpenSSI, released it as open source.