Aria Operations Pre-Upgrade Assessment Warning: "NTP Servers are not reachable" when using Fully Qualified Domain Name (FQDN)

Products

• VCF Operations/Automation (formerly VMware Aria Suite)

Issue/Introduction

The persistent warning "NTP Servers are not reachable" generated by the pre-upgrade assessment tool remains unresolved despite the following considerations:

• The suggested troubleshooting procedures detailed in the knowledge base article Alert Triggered: NTP Servers are not reachable have not resolved the issue.
• An inspection of the ntp.conf configuration file confirms that the NTP server entries are active and have not been commented out.

This warning is produced by the Pre-Upgrade Readiness Assessment Tool for VMware Aria Operations 8.18.x, as further documented here.

 

Environment

Aria Operations 8.x

Cause

The cause of this issue is due to localized DNS or network configuration problem on the Cloud Proxy, specifically triggered by the following sequence:

• Cloud Proxy vApp Configuration Error: The vApp Options on the Cloud Proxy were disabled or improperly configured, leading to the loss of all associated networking properties, including DNS server settings.
• Name Resolution Failure: Due to the unconfigured DNS, the Cloud Proxy is unable to resolve the Fully Qualified Domain Name (FQDN) of the Network Time Protocol (NTP) server.
• Network Connectivity Issue: Even though the NTP server is operational, the Cloud Proxy cannot reach it over the network due to a network connectivity failure.

Resolution

To troubleshoot this issue, validate the Network, DNS, and vApp Properties, ensuring they adhere to the recommended configurations.

1. Network and DNS Verification

To begin troubleshooting, access the Cloud Proxy command line and perform the following checks:

• • Connectivity: Test basic network connectivity by executing ping <NTP_IP>.
  • DNS Resolution: Confirm DNS resolution with the command nslookup <NTP_FQDN>.
  • DNS Server Configuration: Ensure that both Forward and Reverse lookup zones are correctly set up on the DNS server.

2. Review Cloud Proxy vApp Properties

If network and DNS checks are successful, consider reviewing the vApp properties for the Cloud Proxy. For guidance on restoring these properties, refer to the external article: Restoring vApp properties in VMware Aria Operations 8.14 and Later.

Additional Information

If the vApp properties are missing on the Cloud Proxy and manual restoration is not desired, the recommended action is to redeploy a new Cloud Proxy.

Redeployment Steps

1. Redeploy the Cloud Proxy: Deploy a new Cloud Proxy appliance.
2. IP/Hostname Preservation (Optional): If the same hostname and IP address are intended to be reused, ensure the old Cloud Proxy is powered off before powering on the new one.
• NOTE: Powering off the Cloud Proxy will stop data collection for any adapters running on it.
3. Adapter Migration:
• With Collector Groups: If collector groups are configured, adapters should automatically failover and resume collection on other available Cloud Proxies within the group. (See: Configuring Collector Groups).
• Without Collector Groups: After the new Cloud Proxy is deployed and confirmed visible in the Aria Operations UI, any adapters that were previously linked to the old Cloud Proxy must be manually reassociated. This is done by editing the adapter instance within Integrations.
4. Remove Old Cloud Proxy from Aria Operations:
• Navigate to the Cloud Proxies page in the Aria Operations UI.
• Select the old Cloud Proxy from the inventory list.
• Click Delete to remove the old Cloud Proxy from Aria Operations. (Only perform this step after all adapters are successfully moved/reassociated).
5. Clean Up: Once the above steps are complete and the old Cloud Proxy is no longer required, it can be deleted from the inventory list on the Cloud Proxies page in Aria Operations.

Reference Document:

• Configuring Cloud Proxies in VMware Aria Operations
• Configuring Collector Groups