Unix for Large Systems Performance Availability CompatibilityIn developing UTS, Amdahl's UNIX based operating system for the corporate data center, Amdahl designed a set of technologies which can be applied to any UNIX system. These technologies address four areas of concern in the data center, these being performance, availability, security and connectivity. The A+Edition for Solaris addresses each of these areas while ensuring binary compatibility with Solaris.
Solaris is a powerful implementation of UNIX which runs on a range of hardware from the desktop to the large multiprocessor (MP) systems. SunSoft's focus is to provide a robust operating environment that applies across all workloads and supported hardware platforms. Amdahl's approach with A+Edition is to tune Solaris for Sun's high-end MP servers, and maximize performance for heavy commercial workloads.
In developing the A+Edition, Amdahl engineers redesigned a number of internal components of the Solaris kernel to exploit the unique hardware of the Sun4d architecture contained within the SPARCserver 1000 and SPARCcenter 2000 systems. These enhancements more efficiently manage the additional CPUs, increased memory and more numerous file systems within a large server system. Amdahl redefined the parameters of the system to reflect the needs of the large server. This redefinition manifests itself in many different ways.
One example is system memory usage. The memory required for a heavily loaded server is different than the memory required for a small workstation. Since A+Edition only affects the kernel for the SPARCserver 1000 and SPARCcenter 2000 server architecture, Amdahl was able to optimize the memory usage specifically for heavy workloads on the high-end servers.
Other examples of differing design choices are those based upon the number of CPUs configured into the system. As the number of CPUs in the system grows, the overhead associated with supporting these additional CPUs can have a large impact on system performance. Later sections discuss these issues in more detail, and test results indicate how the design choices can impact the system performance.
High system availability is a key requirement of commercial operating systems. Amdahl's UTS product provides a level of availability comparable with MVS. Although the Reliability, Availability, Serviceability (RAS) features provided by the Sun4D hardware architecture does not match what is available on typical 370/390 systems, some of the technologies developed by Amdahl engineers can be applied to the Sun4D systems. The guiding philosophy for availability then is to add items which are appropriate for the set of RAS features available on the system.
All Solaris third-party products and third party hardware peripherals are available and supported without modification on the A+Edition. All Solaris Application Binary Interface (ABI), Application Programming Interface (API), Device Driver Interface (DDI) and Driver Kernel Interface (DKI) standards are maintained. Any application supported on Solaris 2.3 or 2.4 running on the SPARCserver 1000 or SPARCcenter 2000 will run unchanged and without the need to recompile. DDI/DKI compliant device driver binaries will also run unchanged.
Both Amdahl and Sun have tested the A+Edition for binary compatibility using a wide variety of test suites including XPG4, POSIX and SVID3 to ensure exact conformance with the Solaris API. Applications and middleware testing uses many different critical software applications including compilers, relational database management systems (RDBMS), object-oriented system software, and desktop publishing.
