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UNICOS

From Alfawiki
UNICOS
Company typeOperating system suite
IndustrySupercomputing software
PredecessorCray Operating System (COS)
Founded1984
FounderCray Research
ProductsUnix and Linux operating system variants for Cray supercomputers

UNICOS represents a suite of Unix and subsequently Linux operating system variants created by Cray specifically for their supercomputer platforms. It was developed as the successor to the Cray Operating System (COS), introducing capabilities such as network clustering and compatibility layers that allowed integration with certain other Unix systems. Debuting in 1985 alongside the Cray-2, UNICOS was eventually adapted for additional Cray hardware models. Its initial design drew from UNIX System V Release 2, augmented by numerous features from the Berkeley Software Distribution (BSD), including enhancements in networking and file system functionality.

Development

The project initially bore the name CX-OS and started as an experimental system on a Cray X-MP in 1984, prior to the Cray-2's introduction, showcasing the practicality of Unix on supercomputing architectures.

This operating system redesign was part of Cray Research’s broader initiative to update its software portfolio, which included rewriting their primary Fortran compiler—from cft to cft77—in Pascal to achieve better optimization and vectorization performance.

To facilitate users transitioning from COS to UNICOS, a Guest Operating System (GOS) mechanism was incorporated into COS. This allowed UNICOS to operate as a subsystem within COS, sharing resources such as CPUs, memory, and peripheral devices. Instead of accessing hardware directly, the UNICOS kernel communicated through COS’s GOS interfaces.

Among the early adopters was Bell Labs, where Unix innovators like Dennis Ritchie ported elements of their Eighth Edition Unix, including the STREAMS input/output subsystem, onto UNICOS. They also explored a guest environment within UNICOS itself, enabling it to host instances of its own OS.

Releases

Cray introduced multiple operating system variants under the UNICOS brand, including:

  1. UNICOS: the foundational Cray Unix variant based on System V, deployed across platforms such as the Cray-1, Cray-2, X-MP, Y-MP, and C90.
  2. UNICOS MAX: a microkernel built on the Mach architecture designed for the T3D compute nodes, operating alongside UNICOS on host systems like the Y-MP or C90.
  3. UNICOS/mk: a serverized edition utilizing the Chorus microkernel to deliver a distributed operating system, implemented on the T3E. This marked the final OS iteration directly derived from original UNICOS codebases.
  4. UNICOS/mp: based on IRIX 6.5 instead of UNICOS code, this variant was deployed on the X1 system.
  5. UNICOS/lc: built upon SUSE Linux, this version ran on systems such as the XT3, XT4, and XT5. It featured:
    1. compute nodes operating with the Catamount microkernel (originating from Cougaar)
    2. service nodes running SUSE Linux
  6. Cray Linux Environment (CLE): starting with release 2.1, UNICOS/lc was rebranded as Cray Linux Environment.
    1. compute nodes execute a customized variant of Compute Node Linux (CNL)
    2. service nodes utilize SUSE Linux Enterprise Server

These operating system evolutions illustrate Cray's strategic pivot towards Linux-based platforms to improve scalability and compatibility within high-performance computing sectors.

See also

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