"No valid host was found" Displayed During VM Creation Due to Incorrect Flavor

Symptom

When OpenStack is used to create a VM, the message "ERROR nova.conductor.manager Failed to schedule instances: NoValidHost_Remote: No valid host was found." is displayed.

The following information is displayed in the nova-conductor.log file:

Key Process and Cause Analysis

The flavor specifications are incorrect. For example, the size exceeds the local drive space or the memory is insufficient.

Conclusion and Solution

1. Check the flavor used for creating a VM, such as the drive size and memory size.

   openstack flavor list

2. Create a flavor again.

   openstack flavor create <flavor-name> --vcpus 4 --ram 8192 --disk 40

3. Use the flavor that meets the requirements to create a VM again.