What are instance snapshots?
You may want to copy the state of your instance at a particular time and use it later to boot a new instance. These copies are known as snapshots.
Instance snapshots only copy data from the primary root disk of your instance, not from the secondary ephemeral storage or mounted volume storage.
The primary root disk is generally small (10 to 30GB in size) and is not suitable for storing significant amounts of data. Creating a snapshot of your instance is preserving the instance state such as software installation, configurations and profiles. If you have large data on ephemeral storage, you will need to back this up separately. Volumes can also be snapshotted, but must be done though the Volume service.
Why you need snapshots
There are five main reasons you would take a snaphost of your instance:
- To backup the instance and allow you to restore an instance from the snapshot.
- To copy the set-up of an instance and create a template image which can be used to launch instances that are already configured.
- To re-launch an instance as a new instance with a different flavor (increase or reduce the number of VCPUs) or launch in a different Availability Zone.
- To share the set-up of an instance with other users. You need to ensure proper permissions are set for the snapshot image.
- To use the snapshot as a base image to create a volume which can be used to launch an instance.