Here are a few use-cases for bare metal (physical server) provisioning in cloud; there are doubtless many more interesting ones:
- High-performance computing clusters
- Computing tasks that require access to hardware devices which can’t be virtualized
- Database hosting (some databases run poorly in a hypervisor)
- Single tenant, dedicated hardware for performance, security, dependability and other regulatory requirements
- Or, rapidly deploying a cloud infrastructure
ref: https://info.massopencloud.org/blog/anuj-thakur-ironic/
http://events.linuxfoundation.org/sites/events/files/slides/CloudOpenJapan2014_takada_20140508.pdf