Build instance pool and placement configurations with availability domain distribution.
Last verified: May 2026
Build instance pool and placement configurations with availability domain distribution.
Required Fields
compartmentIddisplayNameinstanceConfigurationIdsizeplacementConfigurationsOutput will appear here...OCI Instance Pools let you create and manage groups of identical Compute instances as a single entity, with support for autoscaling, automatic instance replacement, and integration with load balancers. Instance pools use instance configurations (templates) to define the shape, image, networking, and metadata for instances. This builder helps you configure instance pools with placement constraints, fault domain distribution, autoscaling policies, and load balancer backend set attachments.
Autoscaling policies monitor metrics (CPU utilization, memory, custom metrics) and automatically adjust the pool size between configured minimum and maximum instance counts. Threshold-based policies scale out when a metric exceeds an upper threshold and scale in when it drops below a lower threshold. Scheduled policies adjust pool size at specific times (e.g., scale to 10 instances at 8 AM, scale to 3 at 8 PM). Cooldown periods prevent rapid scaling oscillation.
Instance pools automatically detect and replace unhealthy instances. When an instance is terminated, crashes, or fails a health check from the attached load balancer, the pool launches a replacement instance using the same instance configuration. The new instance is placed in the same availability domain and is automatically registered with any attached load balancer backend sets. This self-healing behavior maintains your desired capacity without manual intervention.
Your team's web tier has been running 20 always-on Compute instances ($1,400/month). Traffic is highly predictable — peaks 8AM-6PM weekdays, quiet otherwise. The builder generates an instance pool: VM.Standard.E5.Flex configuration, schedule-based scaling (target size 20 weekdays 8-6, target size 5 otherwise) + threshold-based scaling for unexpected spikes (CPU > 70% adds 5 instances). Distributed across 3 fault domains for HA. Monthly cost drops to ~$580 — 60% savings while maintaining capacity for both normal and unexpected demand.
The builder constructs OCI instance pool configurations with: instance configuration (template defining shape, image, networking, metadata), instance pool resource (configuration reference, target size, fault domain distribution, placement constraints), autoscaling configuration (threshold-based: metric + threshold + scaling delta, schedule-based: cron expression + target size), and load balancer backend set attachment for automatic registration. Output is generated as oci compute-management commands and Terraform oci_core_instance_configuration + oci_core_instance_pool resources.
Always distribute instance pools across all 3 fault domains for HA. The default is automatic distribution but you can override with explicit fault domain placement. Spreading across fault domains protects against rack-level hardware failures within an AZ — different from cross-AZ which protects against AZ failures.
Schedule-based scaling is the right pattern for predictable workloads (business hours, batch processing windows). Threshold-based scaling adds complexity without benefit when traffic is predictable. Combine both: schedules for known cycles + thresholds for unexpected spikes.
Instance pool autoscaling has minimum 5-minute cooldown periods. Tighter cooldowns aren't honored. For aggressive scaling needs, use OKE Cluster Autoscaler with HPA instead — Kubernetes-native autoscaling reacts faster than instance pool scaling.
Was this tool helpful?
Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.