Unraid uses the php api. I can look at managed save as a option which is hibernate to disk
libvirt_domain_suspend
libvirt_domain_suspend($res)
[Since version 0.4.1(-1)]
Function is used to suspend the domain identified by it's resource.
@res [resource]:libvirt domain resource, e.g. from libvirt_domain_lookup_by_*()
Returns:: TRUE for success, FALSE on error
libvirt_domain_managedsave
libvirt_domain_managedsave($res)
[Since version 0.4.1(-1)]
Function is used to managed save the domain (domain was unloaded from memory and it state saved to disk) identified by it's resource.
@res [resource]:libvirt domain resource, e.g. from libvirt_domain_lookup_by_*()
Returns:: TRUE for success, FALSE on error