Architecture

Teradata relies on three architectural components.

• Parsing Engine(PE) or Optimizer
• Access Module Processors(AMPs)
• BYNETs
• Disks

Teradata Architecture

Parsing Engine (PE)
The Parsing Engine (PE) is a component that interprets SQL requests, receives input records, and passes data. It sends the messages through the BYNET to the AMPs.

BYNETs
The BYNET act as message-passing layer. It decides which AMP should receive a message.

Access Module Processor (AMP)
The AMP is a virtual processor (vproc) designed to managing a portion of the entire database.
It performs all database management functions such as sorting, aggregating, and formatting data.
The AMP receives data from the PE, formats rows, and distributes them to the disk storage units it controls. The AMP also retrieves the rows requested by the Parsing Engine.

Disks
Disks are disk drives associated with an AMP that store the data rows.

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Software Components

A Teradata Database node requires three distinct softwares.
TPA
PDE
OS

Trusted Parallel Application (TPA) uses PDE to implement virtual processors (vprocs). The Teradata Database is classified as a TPA. The four components of the Teradata Database TPA are:

AMP (Top Right)
PE (Bottom Right)
Channel Driver (Top Left)
Teradata Gateway (Bottom Left)

Parallel Database Extensions (PDE) 
The Parallel Database Extensions (PDE) software layer was added to the operating system to support the parallel software environment. The PDE controls the virtual processor (vproc) resources.

OS:The Teradata Database can run on the following operating systems:

Microsoft Windows 2000
SuSE Linux
Note:Some customers may still be running on MP-RAS UNIX, but it is no longer supported beyond Teradata 13.

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Cliques

A clique (pronounced, "kleek") is a group of nodes that share access to the same disk arrays. Each multi-node system has at least one clique. The cabling determines which nodes are in which cliques -- the nodes of a clique are connected to the disk array controllers of the same disk arrays.

 
In the event of a node failure, cliques provide for data access through vproc migration. When a node resets, the following happens to the AMPs:

• When the node fails, the Teradata Database restarts across all remaining nodes in the system.
• The vprocs (AMPs) from the failed node migrate to the operational nodes in its clique.
• The PE vprocs will migrate as follows: LAN attached PEs will migrate to other nodes in the clique. Channel attached PEs will not migrate. While that node remains down, that channel connection is not available.
• Disks managed by the AMP remain available and processing continues while the failed node is being repaired.

 
Cliques in a System
 
Vprocs are distributed across all nodes in the system. Multiple cliques in the system should have the same number of nodes.

The diagram below shows three cliques. The nodes in each clique are cabled to the same disk arrays. The overall system is connected by the BYNET. If one node goes down in a clique the vprocs will migrate to the other nodes in the clique, so data remains available. However, system performance decreases due to the loss of a node. System performance degradation is proportional to clique size.

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Disk Arrays

A disk array is a configuration of disk drives that used to manage and distribute data   across the disks while providing fast access and data integrity.

Disk arrays contain the following major components:
SCSI bus 
Physical disks 
Disk array controllers

Teradata Database uses dual redundant disk array controllers for maximum availability and better performance.
Two disk array controllers provides one level of protection in case one controller fails, and provides parallelism for disk access.

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Databases

A Teradata Database system contains one or more nodes. There are two types of Teradata Database systems:

Symmetric multiprocessing (SMP) ­
A Symmetric Multi Processing (SMP) platform consists of a single Teradata Database node. An SMP system has multiple CPUs that work together. All applications run under a single operating system on the node.

The AMPs and PEs on an SMP system communicate through the BYNET software that handles the message queuing and flow control.

Massively parallel processing (MPP) ­
A Massively Parallel Processing (MPP) implementation of the Teradata Database consists of multiple SMP nodes that work together. The nodes are connected through the BYNET, a combination of hardware and software that allows the vprocs (PEs and AMPs) to communicate with each other.

The Teradata Database is a linearly expandable database system because as additional nodes and vprocs are added, the system capacity scales in a linear fashion.

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