Introduction
DBC/1012 is a Database computer that was introduced by Teradata Corporation in 1984. It is a back-end DBMS for mainframe computers. It was designed to manage up to one terabyte databases in size i.e. 1,000,000,000,000 characters. “1012” refers to “1012”.
DBC/1012 Overview
It is an integrated system wherein the RDBMS is implemented in software, hardware, and firmware. It is a dedicated system with one or more host computers and intelligent workstations connected to LAN. It consists of direct access storage devices and multiple microprocessors.
The system is made up of the following components:
- Host System Communication Interface (HSCI)
- Interface Processor (IFP)
- Access Module Processor (AMP)
- Processor Interconnection Network (Ynet)
- System Console and Printer
- Disk Storage Unit (DSU)
- Communication Processor (COP)
These components are described below,
I. Host System Communication Interface
The Host System Communication Interface is responsible for assisting the database requests of the applications and users on the host system. It allows the applications and users to manipulate the database. It consists of following components.
- Call Level Interface (CLI) routines – A library of runtime service routine.
- User to TDP Communication (UTC) – A set of routines that are used to manage the communication between the TDP and application.
- The TDP (Teradata Director Program) – It manages the interaction of interactive users and applications program on host system with DBC/1012. It is also responsible for input/output via an IFP, as well as security and recovery.
II. Interface Processor
The interface processor interfaces both with the Ynet and the host and manages the traffic between them. The number of interface processors depends on the traffic and can be adjusted. The functions implemented in interface processor are following:
- Host Interface
- Parser
- Session Control
- Ynet Interface
- Dispatcher
The Ynet interface controls the transmission of messages. Session control is used to process the logon the logoff requests from host.
The DBC/SQL request is semantically interpreted by the parser. The parser generates a number and sends these to the dispatcher. It controls the execution of work steps. It also sends the response to the host via a response control subsystem.
III. AMPs and DSUs
The AMP is similar to IFP and uses some similar components. It receives requests for database access and then responds by sending required information. Each AMP has two data storage units. The database manager (DBM) is responsible for the functions of retrieving, selecting and storing data into the attached disk storage units (DSUs). The data is replicated and distributed over the DSUs to achieve reliability and concurrency both. The database manager is responsible for manipulation, definition and maintenance and recovery of the tables under control of Access Module processor (AMP). To increase the capacity and performance both additional AMPs and DSUs can be attached to the system.
IV. Ynet
Processor Interconnection Network is an intelligent bus which implements the multiprocessor management and interprocessor message sorting and routing functions in hardware. The interconnection network comprise of dual Ynet buses. To provide fail-safe and reliable operations. It allows messages to be transferred between the processors connected to it (AMPs, IFPs and COP). The basic Ynet configuration is binary tree of three level which consist of eight leaf and seven internal nodes. The processor module is connected at the leaf level. The network contains control information that enables the Ynet to direct the block to the correct destination. The interconnection network which is used is as follows: A user’s request arrives at one of the interface processor (IFP). It determines the nature of the request and then generates a number of works to respond to this request. Data retrieved by the Access Module Processor (AMP) travels up to the network. The control information available in the data blocks is used to sequence the arrival of data blocks from Access Module Processor (AMP) to a given Interface Processor (IFP) in a certain order that achieve merge sorting of the data.
Ynet provides the following type of communication,
- Between any two processors
- A group of processor to single processor
- One processor to group of processor
- Between the processors to synchronize their operations on data.
Ynet can support up to 968 processors.
V. System Console and Printers
The System console is an IBM or a compatible personal computer. It is used for operator communication which monitors the status of the system, which also includes its current performance and configuration. The console is also used in diagnostic operation and in controlling the system. The printer can be used to get a hard copy record of the console’s operation.
VI. COP and MTPD
The communication processor is similar to those functions which are implemented in the IFPs. It is used when an intelligent workstation or a host computer communicates with the DBC/1012 and the communication is established over a LAN (Local Area Network). The communication processor (COP) is a special purpose Interface processor (IFP) each communication processor is connected to both Ynets. The software resident in the host includes the Micro Teradata Director Program (MTDP) and the MOSI (Micro Operating System Interface). The Micro Operating System Interface is collection of routines for interacting with the host operating system and the protocol routines used by the host for communication.
The COP contains the session control, dispatcher subsystem and parser. These subsystems perform analogous tasks.
VII. Data Directory/Dictionary
The DD/D (Data Directory/ Dictionary) contains information about the relations. It also contains the appropriate control information. The relation scheme consists of identification of the owner, its attributes and their domains and creator of these relations, indexes to be maintained and a list of authorised user.
Summary
In the traditional approach of database system, Database Management System runs on same computer. It is necessary to move data to CPU for processing. Now, we have discussed about a number of approaches that can be used to manage database on a separate system. The DBC/1012 provides a number of facilities for database integrity, security and concurrency.