Preemptible instances are instances that may be terminated at any time. This can occur in two cases:
- If 24 hours have passed since the instance was started.
- If there are insufficient resources to launch a regular instance in the same availability zone. The probability of termination is low, but varies depending on the day.
Preemptible instances are available at a lower price than regular instances. However, they don't provide fault-tolerance.
In addition to the fact that preemptible instances can be forcibly stopped, they have the following limitations:
- If there aren't enough resources in the specified availability zone to launch a preemptible instance, it won't launch.
- A preemptible instance can't be turned into a standard VM and vice versa.
- Preemptible stances aren't subject to an SLA.
How to work with preemptible instances
To create a preemptible VM, follow the instructions.
The instance isn't deleted after it's stopped and all its data is saved. When you need the instance again, start it again.
Instance Groups stops preemptible instances in the group not exactly after 24 hours, but after a random interval from 22 to 24 hours. This prevents all instances in the group from restarting at the same time and ceasing to handle the load of running applications.