I never knew much about UNIOS untill recently when i had the idea to lean about super computers. And as i focused my attention onthe operating systems they are running UNIOS was one which powers the 9th rannking computer and is capable of powering all the Cray build super computers. (This contains 4 computers of the first ten). The latter contains what i found out about the operating system form the web. Please note these are adopted form the sites which the link is provided at the end.
what is actually UNICOS?
Unicos (officially all-caps UNICOS) is the name of a range of Unix operating system variants developed by Cray for its supercomputers. Unicos is the successor of the Cray Operating System (COS). It provides network clustering and source code compatibility layers for some other Unixes. Unicos was originally introduced in 1985 with the Cray-2 system and later ported to other Cray models. The original Unicos was based on System V.2, and had numerous BSD features (e.g., networking and file system enhancements) added to it.
The UNICOS system makes extremely flexible and robust calculating machines with support of the following hard and software characteristics possible:
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.
A layered Overview of the architecture of UNICOS
UNICOS could easly scale efficiently to 30,000 processors. This consists of two primary components—a microkernel for compute PEs and a full-featured operating system for the service PEs.(Processing Element).