Collection Station redundancy
This topic can help you understand basic concepts about Collection Station redundancy.
Use the following information to enable redundancy for Collection Stations in your environment.
The following video (2:20) explains how Collection Station redundancy works.https://youtu.be/DJmK3oyukxw
Collection Station redundancy overview
Data collection involves the Collection Agent and Collection Station components. The Collection Agent collects data and sends it to the Collection Station. The Collection Station forwards this data to the Indexers for indexing. If the Collection Station goes down, you start losing data. To support Collection Station redundancy, you need to maintain the availability of the Collection Station.
By maintaining availability of the Collection Station, you can make the following channels more reliable:
- Channel between the Collection Agent and Collection Station (after data is collected).
- Channel between the Collection Station and Indexer (before the collected data reaches the Indexer for indexing).
Redundancy applies only to the Collection Station and does not apply to the Collection Agent. The Collection Agent usually resides on the same computer as the target host (where the data resides) and will only go down if the target host goes down.
The following diagram identifies the channels covered by applying Collection Station redundancy.
How Collection Station redundancy works
To implement Collection Station redundancy, it is imperative that the Collection Stations deployed in your environment are included in a common pool. This pool is automatically created when you select the check box for enabling redundancy while installing the Collection Station. If the Collection Station is installed while performing a typical installation of the product, then it is assumed that you want to enable redundancy. Therefore, in a typical installation the Collection Station is automatically added to the pool. The pool is saved with the name "ITDAPool" in the agent.properties file. For more information, see Modifying the configuration files.
When you upgrade from an earlier version of the product, it is assumed that you want to enable redundancy. Therefore, when you upgrade the Collection Station is automatically added to the pool.
After you implement redundancy, if a Collection Station goes down, the Collection Agents communicating with that Collection Station are redirected to the next available Collection Station and data collection continues. When a Collection Agent contacts the Collection Station for the first time, the Collection Station informs the Collection Agent about the following information:
- Details about the other Collection Stations operating in the pool.
- Details about the sequence in which the Collection Agent must contact the other Collection Stations in case it goes down.
Thus, if the Collection Station goes down, the Collection Agent uses the preceding details to redirect data collection work to the next available Collection Station.
Note that if there are any data collectors configured on the Collection Station and if the Collection Station goes down, those data collectors stop working. It is recommended to use the Collection Station only as a receiver for data forwarded by the Collection Agents and not for actually collecting data. For more information, see Agent types.
If you already have data collectors configured on the Collection Station, you might want to move them. For more information, see the CLI command for moving data collectors.
Collection Agents and redundancy
To successfully implement redundancy, it is important that the Collection Agents deployed in your environment are connected with the pool in which the Collection Stations are operating. This happens automatically when you install or upgrade to the latest version of the Collection Agents.
If you upgrade to the latest version of the product but continue using older Collection Agents, the Collection Agents will not have details of any new Collection Stations that you install. They will continue to contact only those Collection Stations of which they are aware.
The following table compares how data collection works across different versions of the Collection Agent:
|Collection Agents 2.1.00 or later||Collection Agents 2.0.00 or earlier|
While installing the Collection Agent version 2.1.00 or later, you need to provide details of any one Collection Station available in the pool. When the Collection Agent contacts this Collection Station for the first time, the Collection Station provides details of all other Collection Stations in the pool. Furthermore, it provides the order in which the Collection Agent must contact the next Collection Station if the initial Collection Station goes down.
Additionally, if a new Collection Station is added to the pool, then details of this Collection Station is automatically made available to the Collection Agent. Thus, all the Collection Agents in the pool are communicated details about the Collection Stations newly added to the pool.
If you are using Collection Agents with version earlier than 2.1, then the Collection Agents communicate with the Collection Stations in the same way as they did in the earlier version.
In the earlier version, if you provided details of three Collection Stations while installing the Collection Agent, the Collection Agent will first contact the Collection Station that was added initially. If the first Collection Station goes down, then the Collection Agent will contact the second Collection Station. If the second Collection Station also goes down, then the Collection Agent will contact the third Collection Station. The Collection Agent contacts the Collection Stations in the same order as they were added.
Where to go from here
If you are installing the product for the first time, proceed as follows:
- Install multiple Collection Stations in your environment. For more information, see Installing in a multiple-server environment.
- Install Collection Agents that can automatically communicate with the Collection Station pool. For more information, see Setting up Collection Agents.
If you are upgrading from an earlier version of the product, proceed as follows: