Guest OS preference isn't working to define physical hosts to deploy os types

[msinhore]

ISSUE TYPE

• Bug Report

COMPONENT NAME

API, UI

CLOUDSTACK VERSION

4.11.x

CONFIGURATION

Define the OS preference as Windows in one host to take advantage of hardware and OS licensing models.

OS / ENVIRONMENT

Hypervisor: VMware 6.5
Template: Windows Server Datacenter 2016

SUMMARY

If a host is defined to be preferred OS for windows for example, it isn't working. The Windows OS is deployed on any hosts.
This issue occurred with "Windows Server 2019 Datacenter" using os_type "Windows Server 2016 (64-bit)" running on top VMware 6.5.

STEPS TO REPRODUCE

- Setup the OS preference for Windows in one host.
- Deploy a Windows VM.

EXPECTED RESULTS

Windows VM running in target host where Os preference is Windows.

ACTUAL RESULTS

The Instance VM is being deployed in a random host.

[yadvr]

@msinhore can you try deploying a 2016 template (instead of 2019) or any other Windows VM on the hypervisor? The 2019 OS may require secure boot which is not supported I think.

[yadvr]

Investigation: By default, the FirstFitAllocator will try to find and sort available hosts by priority and when a host has the OS preference set (by a "guest.os.category.id" detail in host_details) it will have a higher priority than other hosts when trying to deploy the VM on a host. However, that does not restrict CloudStack/FirstFitAllocator to return and use other hosts, for example the priority host with the guest OS preference set may not have enough capacity or max. guest limit.

The priority set by the FirstFitAllocator is: Hosts with GPU if GPU is required by template/vm > Hosts matching OS preference > HVM requirement matching the template or if host has HVM > rest of the hosts.

[msinhore]

Thank you @rhtyd for you explanation.

[andrijapanicsb]

Why closing this one @msinhore - this is, in my opinion, a bug - or at leasts an undocumented behaviour.

[weizhouapache]

thanks @rhtyd .
what @rhtyd missed is that, if vm has last host_id specified, cloudstack will try to start vm on it at first.
for new vm, it will be deployed to the host as we expect.

[yadvr]

Fixed in #4338