# Unattached boot volume | Cloud Efficiency Hub Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/unattached-boot-volume When a Compute instance is terminated in OCI, the associated boot volume is not deleted by default. By: Charlie Wolfe Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) # Unattached Boot Volume The short version When a Compute instance is terminated in OCI, the associated boot volume is not deleted by default. [Charlie Wolfe](https://www.linkedin.com/in/dcwolfe/) Senior Product Manager @ LogicMonitor OCI service [OCI Block Volume](https://www.pointfive.co/efficiency-hub/cloud-services/oci-block-volume) Category [Storage](https://www.pointfive.co/efficiency-hub/service-category/storage) Reference CER-0199 Type Idle or Unused Resource ## 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. - [Working with Boot Volumes docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Block/Concepts/bootvolumes.htm) - [Terminating an Instance docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Compute/Tasks/terminatinginstance.htm) - [Block Volume Performance docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Block/Concepts/blockvolumeperformance.htm) - [Detached Volume Performance Autotuning docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Block/Tasks/detached-perf.htm) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - OCI Block Volume CER-0208 ### [Unattached Block Volume (Non-Boot)](https://www.pointfive.co/efficiency-hub/inefficiencies/unattached-block-volume-non-boot) 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... Storage - OCI Block Volume CER-0550 ### [Overprovisioned OCI Block Volume Performance Level](https://www.pointfive.co/efficiency-hub/inefficiencies/overprovisioned-oci-block-volume-performance-level) OCI Block Volume bills performance separately from capacity. Each block or boot volume is charged per GB-month for storage plus a number of volume performance units (VPUs) per GB-month set by its performance level: 0 for Lower Cost, 10 for... Storage - OCI Block Volume CER-0551 ### [Excessive OCI Block Volume Backup Retention](https://www.pointfive.co/efficiency-hub/inefficiencies/excessive-oci-block-volume-backup-retention) OCI Block Volume backups are stored in Object Storage and billed at Object Storage prices for as long as they are retained. The Oracle-defined Bronze, Silver and Gold backup policies are a one-click choice, but their retention is fixed and... Storage --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.