Architecture Overview

Abstract

Oracle is designed to be a very portable database—it is available on every platform of relevance, from Windows to UNIX/Linux to mainframes. However, the physical architecture of Oracle looks different on different operating systems. For example, on a UNIX/Linux operating system, you’ll see Oracle implemented as many different operating system processes, virtually a process per major function. On UNIX/Linux, this is the correct implementation, as it works on a multiprocess foundation. On Windows, however, this architecture would be inappropriate and would not work very well (it would be slow and nonscalable). On the Windows platform, Oracle is implemented as a single process with multiple threads. In the past, on IBM mainframe systems, running OS/390 and z/OS, the Oracle operating system–specific architecture exploits multiple OS/390 address spaces, all operating as a single Oracle instance. Up to 255 address spaces can be configured for a single database instance. Moreover, Oracle works together with OS/390 Workload Manager (WLM) to establish the execution priority of specific Oracle workloads relative to each other and relative to all other work in the OS/390 system. Even though the physical mechanisms used to implement Oracle from platform to platform vary, the architecture is sufficiently generalized that you can get a good understanding of how Oracle works on all platforms.