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:
- node1 - Number of AMPs = 10
- node2 - Number of AMPs = 20
- node3 - Number of AMPs = 10
- node4 - Number of AMPs = 20
- 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:
| 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:
- node1 - Number of AMPs = 10
- node2 - Number of AMPs = 20
- node3 - Number of AMPs = 10
- node4 - Number of AMPs = 20
- 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:
| 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.