Compute Service Customization

The nova_override.conf file is a custom configuration file used in Platform9's Private Cloud Director to allow you to override default configurations for Private Cloud Director compute service. These overrides persist across upgrades, ensuring that your customized settings remain intact.

Note that updating nova_override.conf file is an advance operation and should only be performed by Administrators with complete understanding of the option they are editing and the possible impact. We highly recommend that you do this only under guidance from Platform9 support or solution architect teams.

Important

Updating nova_override.conf file is an advance operation and must only be performed by Administrators with complete understanding of the option being edited and side effects / impact if any. We highly recommend doing this only under guidance from Platform9 support team or solution architect team.

The nova_override.conf file is typically located in the following directory.

Bash

/opt/pf9/etc/nova/conf.d/nova_override.conf

Info

The nova_override file must be edited on each hypervisor host where the override configurations are required. This ensures that the custom settings apply consistently across all compute nodes.

You can use this override file to:

• Adjust logging levels or enabling more verbose logging by enabling debug mode. (Mostly commonly used case).

• Customize compute driver options.

• Modify quota defaults for specific tenants.

Here is an example of a nova_override.conf file customized for common use cases like for logging, debugging, and optimization.. For more info, refer to nova.conf.

Logging & Debugging

Safe for troubleshooting but should be reverted in production.

Bash

[DEFAULT]
debug = true  # Enable detailed logging (useful for troubleshooting)
log_dir = /var/log/nova  # Log file storage location

Scheduler Configuration

Can be adjusted to improve VM scheduling behavior.

Bash

[scheduler]
max_attempts = 5  # Number of retries for scheduling instances

Compute Resource Limits

Can be modified based on hardware capacity.

Bash

[DEFAULT]
reserved_host_memory_mb = 2048  # Reserve memory for the hypervisor
cpu_allocation_ratio = 16.0  # Overcommit CPU resources (Default: 16)
ram_allocation_ratio = 1.5  # Overcommit RAM resources (Default: 1.5)

Restart Service

After editing the nova_override.conf file, you must restart the Private Cloud Director compute service for the changes to take effect. Run the following command on the host:

Bash

systemctl restart pf9-ostackhost

Advance Settings

Warning

These settings impact VM operations and performance. Modify only if necessary and test changes in a non-production environment.

Compute Driver Configuration

Bash

[DEFAULT]
compute_driver = nova.virt.libvirt.LibvirtDriver

Do not change unless you are configuring a different virtualization technology (e.g., VMware, Xen, KVM).

Networking Configuration

Bash

[neutron]
service_plugins = router,metering

Changing networking parameters without proper testing may break VM connectivity.

Disk & Storage Settings

Bash

[libvirt]
images_type = qcow2  # Default disk image format
live_migration_flag = VIR_MIGRATE_LIVE

Modify only if you are implementing specific storage optimizations.

CPU Mode and Model Configuration

Bash

[libvirt]
# Specifies the CPU mode for virtual machine instances.
cpu_mode = custom
# Defines the custom CPU model(s) to be used with the hypervisor.
cpu_models = Broadwell-noTSX-IBRS

This configuration is typically used when you need consistent CPU features across different hypervisors.