DETAILS OF UNICOS

                         

UNICOS is the standard operating system for VSMP (Cray Vector Symmetric multi-processor) computers and established since 1985. It was derived from the UNIX System V, a far common and well ported operating system programmed in C. The UNICOS system also was affected by the 4th generation of BSD and extended by super computing abilities to provide high performance to support the science and development market. UNICOS is the first 64 bit implementation of UNIX and a UNIX similar file system. UNICOS system offers a stable base from small servers up to gigantic computer plants.

Characteristics
The UNICOS system makes extremely flexible and robust calculating machines with support of the following hard and software characteristics possible:

Parallel processing
The UNICOS system is the first high performance UNIX based operating system which supports SMP.

Multi-processor and multi-threading operating system
The UNICOS system is scalable on more than 32 processors. Cray aims at a small CPU percentage for the consumption of system processes, also in the greatest and the most extensive configuration.

High performance I/O bandwidth and capacity.
UNICOS I/O scales with the number of processors in the system. The standard UNIX was modified around a file system for up to 8 tbyte to support large files. The support of several devices in a system, multiple types of fixed disks and memory devices in a file system (for build in memory solutions) and the file storage strategy with the used algorithm were specified. Cache support is availably for physical devices in addition to the file system. Through this a high efficiency is made possible for some devices and file systems. The UNICOS system allows combining of buffered and direct access to I/O devices without integrity loss of the data which are not natural for the devices of other systems. For Cray is performance not acceptable without data integrity

Low waiting times for I/O processes
The I'/O path by the UNICOS system is high optimized. As much as possible user data transmittings are finished directly to reduce the need for temporary buffering and copying actions. The UNICOS system created asynchronous I/O for UNIX systems. Many interfaces are designed for the flexible programming to check I/O processes. The UNICOS system contains an optimized path for asynchronous I/O to avoid extra controls or background processes which reduce the total performance. The UNICOS system facilitates I/O in the direct access for the user in most cases as a standard.

Great product extensions
The Batch support is made possible by the NQE/NQS subsystem which is designed completely as a multi-system for the evaluation and control of the jobs. The interaction of many users jobs and processes of a mixed batch and interactive system is protected by job and processing limitations. These limits are made possible by an easy to use administration menu with the name User Database (UDB). Together with the file system and Quotas it allowas the flexible control over users and user groups.

The fairly configured usage planner ensured the safe allocation of resources for users and processes in the two areas batch and interaction mode is possible. Previous planned dates of the mixed processing, that is Batch and interactive mode, is supported by administrative control possibilities .

Extension for the system availability around the processing (for example, checkpoint and restart) can be executed automatically for the support of batch and interactive process recovery. Redundand devices like mirrored fixed harddisks and alternative ways guarantee the fault-tolerant operation. Online diagnoses and ability allowing the control of development problems as CPU error detection and speed reductions.

Multilevel Security (MLS) features like security logging, ACL control, security level and classifications ensure the privacy without influencing of the performance. Settings for the restriction of operator and administrator privileges are possible. Both is a necessary for MLS security and solves a deficit which was recognized by the community.

User accounts were improved for the UNICOS system to guarantee the correctness. On a UNIX system a user can pay for computing time that he has not consumed and is not usual for him. UNICOS system accounts create very detailed recordings for requirements like cost control for computing time and performance analyses.

UNICOS contains an excellent support for tape drives and everything necessary for large systems with multi-volumes and control abilities which are base requirements in a computing centre. Products like the REELlibrarian (CRL) Band Library Management Package and the Cray Data Migration Facility (DMF) are in addition supported for completely transparently data backup to tapes and for automatic or manual recovery.

UNICOS supports the execution of a program on several processors by multitasking. It is the first that contains several function-related interfaces for multitasking and also supports the standard POSIX to protect previous investments in software applications. The UNICOS system supports also the high speed control of thread changes under an application and planned controls to ensure the defined CPU time and resources by the administrator.

The UNIX-based development environment contains a number of applications like Compiler, Loader, Debugger and performance tools.

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