Manage Your Service Limits

Understand, monitor, and manage your tenancy's service limits and compartment quotas. Service limits are resource allowances that limit what resources you can use in your tenancy. They are established when you create your tenancy, but can be changed on request. Compartment quotas are policies that allow administrators to allocate resources to specific compartments with a high level of flexibility.
Service Limits serve the following purposes:
  • Protect you from unplanned surges in consumption and cost by ensuring your users can only use the amount of resources you have predefined.
  • Inform Oracle of the resources you need to run your workload so those resources are always available to you.

Understand the Default Service Limits of Your Tenancy

Enterprise Architect, Cloud Architect, Cloud Operations Manager

Typically, the service limits associated with your tenancy are established when you sign up for Oracle Cloud Infrastructure (OCI).

If you didn't establish limits with your Oracle sales representative or if you signed up through the Oracle Store, then default or trial limits are set for your tenancy. Use the OCI Console or API to view your service limits.

Service Limits serve the following purposes:
  • Protect you from unplanned surges in consumption and cost by ensuring your users can only use the amount of resources you have predefined.
  • Inform Oracle of the resources you need to run your workload so those resources are always available to you.
You are only charged for resources you actually use, regardless of your service limits.

OCI is hosted in regions and availability domains. Regions are localized geographic areas, and availability domains are one or more data centers within a region. Each resource has a defined limit and scope. The scope of a service limit is regional, availability domain, or resource specific. In some cases, the scope is defined by the service. For example, only one NAT Gateway resource is allowed per virtual cloud network.

Follow these best practices to determine the service limits of your tenancy:

  1. Choose your Oracle Cloud Infrastructure regions based on your application, latency, and disaster recovery requirements.
  2. Identify the services that your applications require.

To determine your requirements, review the application architecture, infrastructure code, or on-premises deployment and follow these best practices:

  1. Review the default limits and scope for your required services. For example, per availability domain, per region, or per tenant. Some services have additional limits.
  2. Identify which default service limits require an increase.
  3. Understand the capacity that is required to run your application at peak load, and ensure your limits allow resiliency in the event of the failure of an availability domain.

Monitor and Manage Your Service Limits

Cloud Architect, Cloud Operations Manager

You should regularly evaluate the use of Oracle Cloud Infrastructure services based on your application. Leave room for growth and expansion so you don't inadvertently exceed service limits through the routine use of your application. Keep track of your usage and monitor growth.

  • Use the OCI Console or Service Limits API to capture your current resource utilization and total service limits for your tenancy. For example, how many compute instances you're using per availability domain and how much room you have to grow in that availability domain and region.

  • Request an increase or decrease in the service limit for a resource, if required. Keep a record and track the request. After receiving confirmation, go to the OCI Console or Service Limits API to validate that the service limit has been increased (or decreased).

Set Compartment Quotas

Cloud Architect, Cloud Operations Manager

Administrators use policy statements to create compartment quotas. Compartment quotas control how resources are consumed within each cloud compartment. Administrators use policy statements to create compartment quotas.
  1. Identify services and their quota requirements for each compartment, based on your compartment structure. Quotas set at a parent compartment level, limit resource use for that compartment and all of its children. When setting quotas for a parent compartment, remember to include the usage in child compartments.
  2. Identify the scope of the compartment quotas as availability domain, regional, or global.
  3. Create compartment quota policy statements. When setting a quota that has a scope of availability domain (AD), the quota is allocated to each AD unless you specify a specific AD in the policy. Regional quotas apply to each region.

Be Aware of Fixed Service Limits

Cloud Architect, Cloud Operations Manager

Be aware that some resources have fixed, unchangeable service limits.

Identify those that might impact your applications and make appropriate adjustments to the architecture. For example, you can attach a maximum of 5 security lists to a single subnet. To overcome this limit, you can adjust your architecture to use network security groups in addition to security lists.

Factor Failover Usage in Your Service Limits

Cloud Architect, Cloud Operations Manager

Ensure that you factor in a sufficient gap between the current service limit and the maximum usage to accommodate failover.

When a resource fails, it might still be counted against limits until it is successfully terminated. Ensure that your limits cover the overlap of all failed resources with replacements before the failed resources are terminated. You should consider an availability domain failure when calculating this gap.

  1. Understand your reliability and availability scenario, and how you are making your architecture resilient enough to accommodate that.
  2. Understand your deployment patterns, such as Blue/Green, rollover, or canary.
  3. Have an appropriate buffer on your service limits for failover.
  4. Leave appropriate room for future growth and expansion.

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