Fixed: Unable to Apply DRS Resource Settings on the Host

Issue: Unable to apply DRS resource settings on the host

DRS automatically distributes computing resources such as CPU and memory among virtual machines based on predefined rules. When the error "Unable to apply DRS resource settings on host" occurs, the system fails to implement the resource settings you've configured for the host. This can be due to a variety of reasons.

✤ Network Issues: Poor network connectivity between the host and management server (e.g., a misconfigured switch or faulty cable) can prevent DRS settings from applying. ✤ Insufficient Privileges: The user account may lack the required permissions. Ensure it has administrative rights on the host and virtualization infrastructure. ✤ Software/Firmware Incompatibility: Outdated or incompatible software (e.g., hypervisor or drivers) can cause DRS issues. Ensure everything is up-to-date and compatible. ✤ Resource Overcommitment: If the host is overcommitted on resources, applying DRS settings may fail due to insufficient available resources.

How to fix the "Unable to apply DRS resource settings on host" issue

Now that we know the possible causes, let's go over how to fix the issue step by step.

1. Check Host and Cluster Configuration

The first place to look is your host and cluster configuration. Specifically, ensure that all hosts are configured correctly to support DRS functionality.

• Check CPU Compatibility: If you’re working with a heterogeneous cluster (meaning different host models), make sure the CPU features are compatible across all hosts. DRS cannot properly migrate VMs across hosts if the CPU features aren’t compatible.
• Verify Memory and CPU Settings: Go into your vSphere Client and ensure the memory and CPU settings of the hosts in the cluster are configured appropriately. If a host has restrictive memory or CPU settings, it may not be able to apply DRS settings correctly.
• Examine Affinity Rules: Check for any affinity or anti-affinity rules that may be preventing DRS from applying resource settings on the host. If a VM is bound to a specific host or group of hosts, DRS may fail to apply the settings as expected.

2. Resolve VDS Configuration Conflicts

Distributed Virtual Switch (VDS) mismatches between hosts can prevent DRS from applying resource settings.

• Check Network Configurations: Ensure that all ESXi hosts in your cluster have consistent VDS configurations. Verify that network adapters, VLANs, and port groups are uniformly configured across the hosts.
• Synchronize Settings: If there is a mismatch, synchronize the network settings across the cluster. This will resolve any conflicts that prevent DRS from applying resource settings.

3. Verify Resource Availability

DRS might be unable to apply the resource settings on the host if there aren’t enough resources available. Here’s how you can resolve this:

• Check Resource Utilization: Look at the current CPU, memory, and storage utilization on your hosts. If any host is overburdened, DRS might fail to apply resource settings.
• Free Up Resources: If one or more hosts are underutilized, try migrating VMs manually or adjust resource allocation settings to balance the load across the cluster.
• Increase Host Resources: If you are running a resource-intensive environment, consider adding more CPU or memory resources to the hosts in your cluster.

4. Ensure Proper vCenter Communication

DRS relies on continuous communication between vCenter Server and the ESXi hosts in the cluster. Issues with this communication can lead to errors.

• Check Network Connectivity: Verify that vCenter Server can communicate properly with all hosts. Run basic network checks (ping tests, traceroutes) to make sure there’s no network latency or firewall interference.
• Check vCenter Logs: If the issue persists, review vCenter Server logs to look for any communication issues or errors that may be preventing proper DRS functionality.
• Re-register Hosts: In some cases, re-registering the ESXi hosts in vCenter may help fix the communication issue.

5. Address Licensing and Permission Issues

Ensure that you have the appropriate licensing in place and that you have the required permissions to apply DRS settings:

• Verify Licensing: Check your vSphere license to ensure that it includes the DRS feature. If you’re using an older or lower-tier license, it might not support advanced DRS functionality.
• Check Permissions: If you are working in a multi-admin environment, ensure you have the necessary permissions to configure and apply DRS settings. Check with the administrator if you suspect permission issues.

By following the troubleshooting steps outlined above, you can effectively resolve this error and improve the performance and stability of your VMware environment.

When we successfully resolved the issue of applying DRS resource settings on the ESXi host, ensuring the stable operation of the virtual machine environment, another critical aspect—data backup and recovery—became particularly important.

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💡How to create virtual machine backup automatically in VMware ESXi [Steps]

Step 1. Add VMware ESXi or vCenter devices

✦ Navigate to AOMEI Cyber Backup, then add your VMware device (you can add vCenter Server or Standalone ESXi).

Step 2. Create VMware ESXi VM backup task

✦ Click Backup Task >>Create New Task to schedule VM image backup.

✦ Enter a Task Name and select VMware ESXi Backup as an example.

✦ On Device Name section, select virtual machines you want to backup.

✦ On Target section, specify a location to store VMs. For example, you can backup VM to an external USB drive, network attached hard drives or NAS.

✦ (Optional) On Archive section, enable archiving backup versions to Amazon S3 and click Select to choose the added Amazon S3.

✦ (Optional) On Schedule section, choose full/incremental/differential backup to keep tracking virtual machine data and select the time and frequency (daily/weekly/monthly), which protects business security all the time.

✦ Click Start Backup. It allows you to select start backup now or later.

Step 3. Restore VMware ESXi from backup

(Optional) When a backup is complete, you can restore VM from image backups by clicking the Restore button. Then select a VM backup and click Restore to original location.

Conclusion

Fixing the "Unable to apply DRS resource settings on host" issue requires a methodical approach, starting with checking host configurations and resource availability, resolving any network or VDS conflicts, and ensuring proper vCenter communication.