Block volumes that are not attached to any instance continue to incur charges. These often accumulate after instance deletion or reconfiguration. Unlike boot volumes, unattached data volumes may be harder to track if not labeled or tagged clearly.

When a Compute instance is terminated in OCI, the associated boot volume is not deleted by default. If the termination settings don’t explicitly delete the boot volume, it persists and continues to generate storage charges. Because boot volumes are managed under the Block Volumes service, not within the Compute UI, they’re easy to overlook—especially in environments with frequent provisioning and teardown. Over time, these orphaned boot volumes can accumulate and contribute to unnecessary costs.