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iSeries
Lecture 2
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iSeries architecture
Several architectural features of the iSeries Architecture
distinguish the system from other machines in industry,including UNIX and Windows NT. These features [thefive sacred architectural principles] include:
Technology Independence [ due to the two-part operating
system and TIMI]
Object-based design
Hardware integration
Software integration
Single level store
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iSeries architecture
Several architectural features of the iSeries Architecture distinguish the system fromother machines in industry, including UNIX and Windows NT. These features [the five
sacred architectural principles] include:
Two-part operating system
Technology-independent machine interface (TIMI)
Object-based system
Single-level storage
Separate I/O processors
Multiple data busses
High degree of integration
Open Standards
Logical partitions and many operating systems
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iSeries 800 to 890
http://www-132.ibm.com/content/home/store_IBMPublicUSA/en_US/eServer/iSeries/hardware/medlarge/890/index.htmlhttp://www-132.ibm.com/content/home/store_IBMPublicUSA/en_US/eServer/iSeries/hardware/smallmed/800/index.html8/10/2019 AS400 Architecture Basics
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Two-part operating system
There are two components to the operating system software on aniSeries server.unique in the industry. The two components are System Licensed Internal Code(SLIC) and
Operating System/400(OS/400).
SLIC provides the TIMI with
process control resource management
integrated SQL database
Security
Communications
file system
temp storage JVM, and other primitives.
SLIC is a layer of software at the lowest level, much like a Unix kernel,only far more functional.
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Two-part operating system (cont.)
Operating System/400(OS/400).
Provides the functions that present and work with these
services to the user and to applications.
OS/400 also provides a vast range of high-level
language (such as C/C++, COBOL, RPG, FORTRAN)
runtime functions.
OS/400 interacts with the client-server graphical user
interface [iSeries Navigator].
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Technology-Independent Machine Interface
SLIC, is the Optimizing Translatorconverts applications
to the proper instruction set for the processor. After
translation, which is much like the last part of a compile
process, the resultant code is maintained with the program
object, for reuse.
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Two-part operating system (cont.)
In iSerieschanges to processor hardware and firmware do notaffect the operating system
middleware or
business applications.
The heart of this ability to change without disrupting customers andtheir applications is the Technology-Independent Machine Interface (TIMI).
Applications do not have to rewritten or even recompiled to exploit
new hardware technologies.
This permits only iSeries servers to make technology advances inthe hardware, such as storage, memory, and processor technology,while protecting end-users' investments in existing applications
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Two-part operating system (cont.)
All iSeries models
smallesta few hundred users Largesthundreds of thousands of users
share the same software architecture, including the TIMI.
This permits applications to scale across the entire product line,
from the smallest to the largest models.
48-bit [CISC]64-bit [RISC]
Digital Equipment case !! 3264 128-bit ?
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Object-based system
OS/400 keeps all information as objects.
All program and operating system information, such as: user profiles, database files, programs, printer queue etc. has its
associated object type stored with the information.
In the iSeries architecture, the object type determines
how the object can be used (which methods). For example, it is impossible to corrupt a program object by
modifying its code sequence data, as if it were a file. Becausethe system knows the object is a program, it will only allow validprogram operations (run, backup). Thus, with no write method,
iSeries program objects are immune to a true virus.
Simple stream data files, such as MP3 audio files, are stored asstream-file objects with familiar open, read, and write operations.
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Object-based system
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Single-Level Storage
The iSeries architecture specifies a single very, very large virtualaddress space known as Single-Level Storage (SLS).
All objects, programs, files, users, data, working space, databasetables... everything, resides in this storage space.
This storage space is addressed using 128-bit pointers. It is divided
into sections, including Temporary and Persistent. This distinctionrefers to betweenre-boots. For examples, a user profile is inPersistent, and a shared memory segment is in Temporary.
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Single-Level Storage
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Separate I/O processors and multiple data busses
The hardware side of the iSeries architecture emphasizes the use ofspecialized, intelligent I/O).
Tasks such as disk, network, tape, and terminal I/O are offloaded toa variety of dedicated processors, allowing the main processor(s) towork on application execution.
Most of these I/O processors are PowerPC-based high-speed RISC
processors running a small, self-contained operating system.
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High Degree of Integration
Another defining characteristic of the iSeries architecture is the highdegree of integration both above and below the TIMI.
For example, DB2 for OS/400 is a native relational database managementsystem. That is, DB2/400 is shipped with every system and highlyintegrated into the licensed internal code and the operating system.
The following are areas of iSeries's integration:
Relational database management system (DB/2 for OS/400) Transaction monitor
Communications
Security
Internet serving
User and group administration
Printer management
Job (process) management Backup and recovery
Online help
Electronic customer support
System and network management
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Open standards
The iSeries heritage is based on integrationemphasis has been on providing anintegrated solution.
Although OS/400 is proprietary, IBM has insured an iSeries focus on "open" systemapplications. OS/400 provides numerous industry standards which facilitateapplication portability from other platforms and interoperability with other hardwareplatforms.
IBM's strategy for implementing POSIX, Single UNIX Specification and XPG4 functionshas been to provide APIs and system interfaces that are most valuable to most
vendors developing commercial business applications. OS/400 portability supportincludes:
Asynchronous signals
BSD sockets
Environment variables
Interprocess communication (IPC)
File Systems
POSIX file system Process control
TCP/IP
TI-RPC
Multi-threading (both POSIX and Java)
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Logical partitions and many operating systems
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Logical partitions and many operating systems
iSeries is theuniversal server.
OS/400
Linux
Unix,
Windows
applications all run on iSeries servers.
A single server may optionallybe divided into several partitions, eachof which receives a dedicated set of resources, including processorand memory.
The primary partition must be OS/400, but the other partitions can run,as of this writing, different versions of OS/400 and Linux.
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Logical partitions and many operating systems (cont.)
Linux distributions, provided by several vendors, run in logicalpartition(s) of an iSeries server.
Windows applications run on an iSeries server on an optional plug-in Intel processor.
Rather than run an instance of a Unix operating system, applicationsfrom AIX run inside an OS/400 job, completely and seamlessly
integrated into OS/400. This option is the OS/400 Portable Application Solution Environment
(OS/400 PASE). PASE provides a very easy way to drop in, oftenunmodified, a Unix application on iSeries.
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Open standards
The iSeries heritage is based on integrationemphasis has been on providing anintegrated solution.
Although OS/400 is proprietary, IBM has insured an iSeries focus on "open" systemapplications. OS/400 provides numerous industry standards which facilitateapplication portability from other platforms and interoperability with other hardwareplatforms.
IBM's strategy for implementing POSIX, Single UNIX Specification and XPG4 functionshas been to provide APIs and system interfaces that are most valuable to most
vendors developing commercial business applications. OS/400 portability supportincludes:
Asynchronous signals
BSD sockets
Environment variables
Interprocess communication (IPC)
File Systems
POSIX file system Process control
TCP/IP
TI-RPC
Multi-threading (both POSIX and Java)