# Low-Utilization OCI Instances Not Using a Burstable Baseline Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/low-utilization-oci-instances-not-using-burstable-baseline Some OCI virtual machines are idle most of the day and only need full CPU for short spikes, the workloads Oracle lists for burstable instances:... By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version Some OCI virtual machines are idle most of the day and only need full CPU for short spikes, the workloads Oracle lists for burstable instances: development and test servers, CI/CD runners, monitoring systems, small microservices and static web servers. PointFive Research Cloud cost research at PointFive OCI service [OCI Compute Instances](https://www.pointfive.co/efficiency-hub/cloud-services/oci-compute-instances) Category [Compute](https://www.pointfive.co/efficiency-hub/service-category/compute) Reference CER-0547 Type Suboptimal Tier or SKU ## Explanation Why the waste happens and who it affects. On a regular flexible shape they are charged for every configured OCPU every hour, even though average use is a small fraction of it. OCI lets VM.Standard3.Flex, VM.Standard.E3.Flex, VM.Standard.E4.Flex and VM.Standard.E5.Flex instances run as burstable instances with a baseline of 12.5% or 50% of each OCPU, billed at the baseline, while still being able to burst to the full OCPU count. Oracle's Cloud Advisor has a dedicated Change Compute Instances to Burstable recommendation for this pattern, and it calculates savings directly as the baseline fraction: moving to a 12.5% baseline costs 12.5% of the regular OCPU charge. The lever is different from rightsizing, because the instance keeps its OCPU count and memory, so the change suits workloads whose occasional peaks rule out a smaller shape. ## Billing model The pricing dimensions that drive this cost. Burstable and regular instances on the same flexible shape differ only in how OCPUs are charged. Regular flexible instance Charged for the total configured OCPU count every hour, even if usage is lower Burstable baseline OCPU Charged at 12.5% or 50% of each configured OCPU, the same whether usage is below, at or above the baseline Memory Charged on the amount configured, the same as a regular instance; memory does not burst Windows Server license Charged according to the baseline OCPU on burstable instances ## How to detect 4 checks to find it in your estate. - Review Cloud Advisor's Change Compute Instances to Burstable recommendation: it checks VM.Standard3.Flex, E3.Flex and E4.Flex instances over 24 hours (48 CPU data points) and flags those with 5 or fewer points above 50% or 12.5% Max CPU, P95 CPU below 40% or 10%, and a memory-to-core ratio under 12 GB per OCPU - For shapes and patterns Cloud Advisor does not cover, such as VM.Standard.E5.Flex, chart CpuUtilization (Max and P95) in the oci\_computeagent namespace over several weeks to find instances with low sustained CPU and short spikes - Prioritize non-production compartments and workload types Oracle lists as burstable fits: development and test, CI/CD, monitoring, microservices and static websites - Exclude instances that use features burstable instances do not support: dedicated virtual machine hosts, preemptible capacity, capacity reservations and extended memory VMs ## How to fix 5 ways to remove the waste. - Change eligible instances to a burstable configuration with Change shape, selecting a 12.5% or 50% baseline; Oracle recommends the baseline that matches the threshold the recommendation flagged - Use the Cloud Advisor fix-it flow where available; it also switches the instance to paravirtualized networking, which burstable instances require, so plan for that change on instances using SR-IOV - Schedule the change: a running instance is rebooted during a shape change, and secondary VNICs may need to be reconfigured afterwards - Keep regular instances for production or CPU-critical workloads: bursts are limited to one continuous hour, the host is oversubscribed so bursting and maximum network bandwidth are not guaranteed, and memory does not burst - After the change, watch CpuUtilization for sustained use at the baseline, which means the instance needs the 50% baseline or a regular configuration ## Documentation Vendor references for pricing and configuration. - [Burstable Instances docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Compute/References/burstable-instances.htm) - [Cost Management Recommendations docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/CloudAdvisor/Concepts/recommendations-costmanagement.htm) - [Changing the Shape of an Instance docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Compute/Tasks/resizinginstances.htm) - [Compute Instance Metrics docs.oracle.com](https://docs.oracle.com/en-us/iaas/Content/Compute/References/computemetrics.htm) - [Cloud Price List oracle.com](https://www.oracle.com/cloud/price-list/#pricing-compute) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - OCI Compute Instances CER-0046 ### [Underutilized Compute Instance](https://www.pointfive.co/efficiency-hub/inefficiencies/underutilized-compute-instance) OCI Compute instances incur cost based on provisioned CPU and memory, even when the instance is lightly loaded. Instances that show consistently low usage across time, such as those used only for occasional tasks, test environments, or... Compute - OCI Compute Instances CER-0546 ### [Idle OCI Compute Instances](https://www.pointfive.co/efficiency-hub/inefficiencies/idle-oci-compute-instances) OCI compute instances keep billing for their OCPUs and memory for as long as they are running, whether or not they do any work. Instances are left running after a proof of concept ends, a test cycle finishes, a workload is migrated... Compute - OCI Compute Instances CER-0548 ### [Instances on Previous-Generation OCI Compute Shapes](https://www.pointfive.co/efficiency-hub/inefficiencies/instances-on-previous-generation-oci-compute-shapes) Older OCI tenancies often still run VMs on shapes that Oracle lists as previous generation, orderable only until 2020 to 2022 for most series, such as VM.Standard1, VM.Standard.B1, VM.Standard2, VM.Standard.E2, VM.Standard.E3 and... Compute --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.