Hi,

In a prototype, we have improved Nova's scheduling error messages.

This helps both developers and end users better understand the

scheduler problems that occur on creation of an instance.

When a scheduler error happens during instance creation via the nova

upstream, we get the following message on the Overview tab

(Horizon dashboard): "No valid host was found." This doesn't give us

enough information about what really happened, so our solution was to

add more details on the instance's overview page, e.g.:

**Fault:Message** attribute provides a summary of why each host can not

satisfy the instance’s resource requirements, e.g. for controller-0, it

indicates “No valid host was found. Not enough host cell CPUs to fit

instance cell” (where cell is a numa-node or socket).

**Fault:Details** attribute provides even more detail for each

individual host, for example it shows that the instance “required” 2

CPU cores and shows the “actual” CPU cores available on each “numa”

node: “actual:0, numa:1” and “actual:1, numa:0”.

These details are also present using the OpenStack CLI, in the

_fault_ attribute:

- openstack server show <instance>  

With that in mind, we'd like to know if you are open to consider such

a change. We are willing to submit a spec and upstream that

implementation.

Regards,

- nicodemos