In the Data Collector List page in CA PC admin, the Data Collector has the status Unknown due to wrong DCM_ID environmental variable.
This is probably caused by an attempt to remove a former collector or reinstalling the collector.
The new DCM_ID will not match with the one in the DA and the Collector will have a status Unknown due to wrong DCM_ID environment variable.
All supported releases of Performance Management
Component: Data Collector
Note: If the DC belongs to a non-default IP domain there are some extra steps to do, please contact CA Support for assistance.
The proper process to reinstall or move a DC when you want it to resume polling for existing devices is as follows:
1. Obtain the ID of the DC you'd like to replace. This is shown in the DA admin view for the DCs in the ID column. Or you can get it from REST with this call: http://<da-name>:8581/rest/dcms look for the <DcmID> tag
2. Shut down the DC you want to replace. It is recommended to go to the host and shutting it down using:
systemctl stop dcmd activemq
3. Uninstall the DC that you want to replace.
4. On the system where you will install the replacement DC set the environment variable DCM_ID to the string DcmID you collected in step one.
For example: export DCM_ID=<DC_Hostname>:b25abfe9-f51b-4a21-b75c-59a23dde5bbf
5. Run the DC installer on the new system, the newly installed DC will take on the identity of the one you've replaced
6. After the newly installed DC connects to the DA it will start loading up poll configurations, and begin polling within a few minutes.
IMPORTANT: You don't want to ever have two DCs running with the same ID, so you must ensure that the original is uninstalled such that it can't be inadvertently restarted.