Explanation
Why the waste happens and who it affects.
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.
Billing model
The pricing dimensions that drive this cost.
OCI charges for provisioned block volume storage per GB per month, plus volume performance units (VPUs) per GB per month for performance levels above Lower Cost, regardless of whether the volume is actively attached to a compute instance. This applies equally to boot volumes and data volumes. Detached boot volumes incur charges unless explicitly deleted.
How to detect
2 checks to find it in your estate.
- Boot volume lifecycle state is "AVAILABLE" (attached boot volumes also report AVAILABLE, so state alone is not enough)
- No boot volume attachment in ATTACHED state references the boot volume (check with ListBootVolumeAttachments)
How to fix
4 ways to remove the waste.
- Delete unattached boot volumes that are no longer needed
- Set preserve-boot-volume to false (or select Permanently delete the attached boot volume) in termination automation and IaC so boot volumes are deleted unless explicitly retained; OCI has no lifecycle policy that deletes them later
- Enable detached volume auto-tune on boot volumes that must be kept, so their performance level drops to Lower Cost (0 VPUs/GB) after 14 days detached
- Periodically audit the Block Volumes service for orphaned resources
Documentation
Vendor references for pricing and configuration.