Public Cloud | Default Target Group for Elasticity Scale | Teradata DSA - 17.20 - Public Cloud: Default Target Group for Elasticity Scale Out/In - BAR - Data Stream Architecture

Teradata® DSA User Guide

Product
BAR
Data Stream Architecture
Release Number
17.20
Release Date
October 2021
Content Type
User Guide
Publication ID
B035-3150-101K
Language
English (United States)

Beginning with DSA release 16.10, when DSC is deployed in the Public Cloud with ClientHandler installed on all the nodes, a default target group is created automatically. This default target group expands and shrinks when a database system scales out or in (you may see fold/unfold on some parameters).

The name of the default target group is as follows:

defaultDFTGsystem_name

where DFTG is disk file system target group and system_name is the name of the system.

The following events trigger the creation of the default target group:

  • Configuring or reconfiguring a system
  • Adding a backup solution
  • Adding, deleting or restarting a media server

See the following examples of each scenario.

Default Target Group Example - Configuring or Reconfiguring a System

When a system is configured, a new system configuration is created to represent the nodes associated with the system. If all nodes have ClientHandler installed, a default target group is created. The number of devices allocated is based on the node level soft limit of the system load. See the following example:

System1 has four nodes. All nodes have ClientHandler installed.
  • node1 - Number of AMPs = 10
  • node2 - Number of AMPs = 20
  • node3 - Number of AMPs = 10
  • node4 - Number of AMPs = 20
The backup solution is defined for disk file system with two paths:
  • File system name: /path1/ Max number of open files: 100
  • File system name: /path2/ Max number of open files: 400

The default target group is created with the following configuration:

Target group name: defaultDFTGSystem1
Media Server File System Path Devices
ms1 /path1 2
  /path2 8
ms2 /path1 4
  /path2 16
ms3 /path1 2
  /path2 8
ms4 /path1 4
  /path2 16

ms1, ms2, ms3, ms4 are media servers on node1, node2, node3, and node4 respectively.

Default Target Group Example - Creating a Backup Solution

If a new backup solution is created based on the preceding system, a new default target group is created. See the following example:

System1 has four nodes. All nodes have ClientHandler installed.
  • node1 - Number of AMPs = 10
  • node2 - Number of AMPs = 20
  • node3 - Number of AMPs = 10
  • node4 - Number of AMPs = 20
The backup solution is defined for disk file system with three paths:
  • File system name: /path1/ Max number of open files: 100
  • File system name: /path2/ Max number of open files: 400
  • File system name: /path3/ Max number of open files: 500

The default target group is created with the following configuration:

Target group name: defaultDFTGSystem1
Media Server File System Path Devices
ms1 /path1 1
  /path2 4
  /path3 5
ms2 /path1 2
  /path2 8
  /path3 10
ms3 /path1 1
  /path2 4
  /path3 5
ms4 /path1 2
  /path2 8
  /path3 10

ms1, ms2, ms3, ms4 are media servers on node1, node2, node3, and node4 respectively.

Default Target Group Example - Adding, Deleting, or Restarting a Media Server

During unfolding, for example, from 4 to 8 nodes, 4 new nodes are added. Once all 8 nodes have ClientHandler installed, a default target group is created with all 8 media servers.

If a default target group already existed with 4 media servers, a new configuration is created with the new set of 8 media servers.

During folding, for example from 8 to 4 nodes, 4 nodes are removed from the system and the media servers on the nodes go offline. A new configuration (and default target group) is created with the available 4 media servers.

Restarting a media server behaves the same way as adding a new media server. A default target group is created after all the media servers are available.