You can choose the type of host capacity to use when launching compute instances. On-demand capacity is the default, but you can use preemptible capacity, capacity reservations, or dedicated capacity instead.
- On-demand capacity: Pay for only the compute capacity that you use. With on-demand capacity, you pay for compute capacity by the second, and depending on the shape, you pay only for the seconds that your instances are running. Capacity availability is not guaranteed when launching large workloads.
- Preemptible capacity: Preemptible capacity allows you to save money by using preemptible instances to run workloads that only need to run for brief periods or that can be interrupted when the capacity is reclaimed. Preemptible instances behave the same as regular compute instances, but the capacity is reclaimed when it's needed elsewhere, and the instances are terminated. For more information, see Preemptible Instances.
- Reserved capacity: Reserve capacity for future usage, and ensure that capacity is available to create compute instances whenever you need them. The reserved capacity is used when you launch instances against the reservation. When these instances are terminated, the capacity is returned to the reservation, and the unused capacity in the reservation increases. Unused reserved capacity is metered differently than used reserved capacity. For more information, see Capacity Reservations.
- Dedicated capacity: Run VM instances on dedicated servers that are a single tenant and not shared with other customers. This feature lets you meet compliance and regulatory requirements for isolation that prevent you from using shared infrastructure. You can also use this feature to meet node-based or host-based licensing requirements that require you to license an entire server. For more information, see Dedicated Virtual Machine Hosts.
Service limits and compartment quotas apply to all types of host capacity. For reserved capacity, if your request for reserved capacity will exceed your service limits, request a service limit increase before you reserve the capacity. For more information, see Service Limits.