Some weeks ago, I went through a situation where client monitoring OEM agent was not able to connect to Oracle Enterprise Manager to monitor the Oracle Zero Data Loss. We received the error message below:
“Communication between the Oracle Management Service to the Agent is unavailable. Any features or displayed information requiring this communication will be unavailable.”
“Metric evaluation error start – Unable to connect to the agent.”
After opening an Oracle Service Request, we found the solution by adding new routes on OEM server sending connections between client agent and OEM via administrative network, instead of ingest network, which for some reason stopped working (customer network maintenance for example) and connections started working.
To add this new route, you need to follow the configuration below, to commit the change in real time, for example:
/sbin/ip route add 10.0.0.7/21 dev eth0 table 220
/sbin/ip rule add from 10.0.0.7/21 table 220
/sbin/ip rule add to 10.0.0.7/21 table 220
If you want to make it permanent, add to the end of route-eth0 files the following configuration:
/etc/sysconfig/network-scripts/route-eth0:
10.0.0.7/21 dev eth0 table 220
If you want to make it permanent, add to the end of rule-eth0 files the following configuration:
/etc/sysconfig/network-scripts/rule-eth0:
from 10.0.0.7/21 table 220
to 10.0.0.7/21 table 220
You can delete the configuration in real time by running del command:
/sbin/ip route del 10.0.0.7/21 dev eth0 table 220
/sbin/ip rule del from 10.0.0.7/21 table 220
/sbin/ip rule del to 10.0.0.7/21 table 220
And removing the lines added on files.
Reference: Configuring Exadata Database Server and ZDLRA Routing (Doc ID 1306154.1)
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