The storage that is included on each node in the cluster is ephemeral fast SSD.
By default we do not guarantee the safety of any new data you create on your cluster. The underlying VMs running your code could be replaced at any moment for maintenance. When that happens your containers are safely migrated to new servers, but without any data created in any mounted volumes.
Consider the local storage as a temporary cache to use between deployments.
Do not store there any important data as it will be lost.
Normally all data you store in your container will be lost on every Pull and Deploy. But if for performance reasons you want to cache some data between deployments you can use the /cache directory.
/cache is automatically available in your filesystem and is mounted on the host machine.
Permanent storage is an additional service that can be purchased separately and it's charged per GB.