When you provision an Oracle Base Database, an Oracle Exadata VM Cluster, or a Oracle HeatWave with one or more HeatWave nodes, you specify an network address using CIDR notation, which is a range of networking addresses the service uses. Additionally, when you provision an Oracle Exadata System, which includes VMs and database nodes within it, you also specify a network address range with CIDR. This document explains how those CIDR ranges are used within Oracle Database Service for Azure, and how to select the appropriate space based on the service you are provisioning.

Reserved = 5 // Azure reserves the first 4 IPs and last IP in the CIDR range
UsedIps = Number of IPs already in use in the subnet // Zero when creating a new McVCN
if ( (CidrSize - Reserved - UsedIps) < RequiredIps )
  Error: CIDR size is insufficient to support the requested DB shape

Oracle Base Databases require, during provisioning, the capability to create or update a resource group and dashboard.

Database provisioning launch workflows can occasionally fail due to an IP address conflict issue when Multicloud Virtual Cloud Network (MCVCN) operates in automatic routing mode.

In automatic routing mode, Multicloud Virtual Cloud Network (MCVCN) configures an internal load balancer (ILB) in the leaf VNET, and assigns IP addresses given to a database node over in the Oracle Cloud Infrastructure (OCI) VCN side. This works well for most scenarios. Here is where and why it fails.

When the database IP address falls in one of first 4 IP addresses or the last IP address of the subnet range, Microsoft Azure rejects the private IP address configuration request. The first 4 IP addresses and the last IP addresses within a subnet range are reserved by Microsoft Azure (see Microsoft Azure Virtual Network FAQ).

As an example, assume that a subnet is spawned with a /24 CIDR, the most common subnet configuration, the CIDR means approximately 2% of the database provisioning launch workflows will fail because VCN randomly picked an IP address within a subnet. The failure rate is higher with a smaller CIDR subnet ranges.

The third and fourth IP addresses (which for 10.0.0.0/24 would be 10.0.0.2 and 10.0.0.3) are reserved in Microsoft Azure but usable in OCI. The database provisioning workflow automation has been adjusted to properly reserve these IP addresses. The issue will occur when manual configuration and incorporation of OCI resources is done.

To submit a support request, use the following steps.

1. From the OracleDB for Azure Home page, select the Support icon.
2. This is the Support requests page. You can create, view, and manage support requests assigned to your account. Select the Create a support request link to create a new request.
3. This is the Problem description page of the Create support request flow. You can select options like Billing, Service and subscription limits (quotas), or Technical as appropriate.
4. The pages that follow will vary based on the type of support request you are filing. There are three (3) pages to each type, the Problem description page, the Additional details page, and the Review + create page.
5. On the Review + create page, the Create button, as shown, will only be enabled when you have entered acceptable values into all the required support request fields.
6. Continue to monitor and respond to the request as needed on the Support requests portal.

From any database blade, you will see a Metrics icon in the row of management icons for that database. On a fully functioning database, that icon will be enabled. Here are some actions to take to resolve that issue.

If you select a database and open the Applications Insights Portal and the Metrics blade and no metrics are being displayed, here are some actions to take to resolve that issue.

1. You have not selected an appropriate Metrics Namespace. By default, the metrics open in the Log-based metrics namespace. By default, the starting Metrics Namespace is the Log-based Metrics namespace. For an Oracle Autonomous Database Serverless, an Oracle Exadata Database, an Oracle Base Database, or a Oracle HeatWave Database, you will need to select the namespace as follows:

   Table 1-5 Metrics Namespace

   Database Type	Metrics Namespace
   Oracle Autonomous Database Serverless	oci_autonomous_database
   Oracle Exadata Database	oci_database
   Oracle Base Database	oci_database
   Oracle HeatWave Database	oci_mysql_database

2. You have not selected an appropriate metric for your database. Select from the available metrics in the drop-down field.
3. You have not selected an appropriate time and date range for your metrics.
4. Your database is new, and the metrics are not yet available.

When you reach the service limit (quota) for your account, you receive an error when you try to provision a new database. You must either submit a support request to increase your limit in order to provision that additional database, and wait until that is approved to provision, or you must terminate an existing database to free resources, like CPU or storage, sufficient for your new provisioning request.

When provisioning an Oracle Base Database, you may not see your Microsoft Azure VNET in the list of available resources. If you don't see it in the list, your VNET cannot be peered with an Oracle Cloud Infrastructure (OCI) Multicloud Virtual Cloud Network (MCVCN) due to Microsoft Azure routing limitations.