Before you set up an Exadata DB system, you must set up a virtual cloud network (VCN) and other Networking service components. This topic describes the recommended configuration for the VCN and several related requirements for the Exadata DB system.
At least two subnets in the VCN. The two subnets are:
In general, Oracle recommends using regional subnets , which span all availability domains in the region. If you instead use AD-specific subnets , both the client and backup subnets must be in the same availability domain. The important thing to know for your DB system is that the resources you create in the two subnets must be in the same availability domain. For more information, see About Regional Subnets.
You will create custom route tables for each subnet. You will also create security rules to control traffic to and from the client network and backup network of the Exadata compute notes. More information follows about those items.
Option 1: Public Client Subnet with Internet Gateway
This option can be useful when doing a proof-of-concept or development work. You can use this setup in production if you want to use an internet gateway with the VCN, or if you have services that run only on a public network and need access to the database. See the following diagram and description.
Separate custom route table for the private backup subnet, with one rule:
The same rule as for the client subnet: for the service CIDR label called All <region> Services in Oracle Services Network, and target = the service gateway. This rule enables the backup subnet to reach the regional Object Storage for backups.
Static route on the DB system's compute nodes (to enable access to Object Storage by way of the backup subnet).
Requirements for IP Address Space
If you're setting up Exadata DB systems (and thus VCNs) in more than one region, make sure the IP address space of the VCNs does not overlap. This is important if you want to set up disaster recovery with Oracle Data Guard.
The two subnets you create for the Exadata DB system must not overlap with 192.168.128.0/20.
The following table lists the minimum required subnet sizes, depending on the Exadata rack size. For the client subnet, each node requires two IP addresses, and in addition, three addresses are reserved for Single Client Access Names (SCANs). For the backup subnet, each node requires one address.
The Networking service reserves three IP addresses in each subnet. Allocating a larger space for the subnet than the minimum required (for example, at least /25 instead of /28) can reduce the relative impact of those reserved addresses on the subnet's available space.
Client Subnet: # Required IP Addresses
Client Subnet: Minimum Size
Backup Subnet: # Required IP Addresses
Backup Subnet: Minimum Size
Base System or Quarter Rack
(2 addresses * 2 nodes) + 3 for SCANs + 3 reserved in subnet = 10
/28 (16 IP addresses)
(1 address * 2 nodes) + 3 reserved in subnet = 5
/29 (8 IP addresses)
(2 * 4 nodes) + 3 + 3 = 14
/28 (16 IP addresses)
(1 * 4 nodes) + 3 = 7
/29 (8 IP addresses)
(2* 8 nodes) + 3 + 3 = 22
/27 (32 IP addresses)
(1 * 8 nodes) + 3 = 11
/28 (16 IP addresses)
VCN Creation Wizard: Not for Production
The Networking section of the Console includes a handy wizard that creates a VCN along with related resources. It can be useful if you just want to try launching an instance. However, the wizard automatically creates a public subnet and an internet gateway. You may not want this for your production network, so Oracle recommends you create the VCN and other resources individually yourself instead of using the wizard.
DNS: Short Names for the VCN, Subnets, and DB System
For the nodes to communicate, the VCN must use the Internet and VCN Resolver. It enables hostname assignment to the nodes, and DNS resolution of those hostnames by resources in the VCN. It enables round robin resolution of the database's SCANs. It also enables resolution of important service endpoints required for backing up databases, patching, and updating the cloud tooling on an Exadata DB system. The Internet and VCN Resolver is the VCN's default choice for DNS in the VCN. For more information, see DNS in Your Virtual Cloud Network and also DHCP Options.
When you create the VCN, subnets, and Exadata, you must carefully set the following identifiers, which are related to DNS in the VCN:
VCN domain label
Subnet domain label
Hostname prefix for the Exadata DB system
These values make up the node's fully qualified domain name (FQDN):
In this example, you assign exacs as the hostname prefix when you create the Exadata DB system. The Database service automatically appends a hyphen and a five-letter string with the node number at the end. For example:
Requirements for the VCN and subnet domain labels:
Recommended maximum: 14 characters each. The actual underlying requirement is a total of 28 characters across both domain labels (excluding the period between the labels). For example, both of these are acceptable: subnetad1.verylongvcnphx or verylongsubnetad1.vcnphx. For simplicity, the recommendation is 14 characters each.
No hyphens or underscores.
Recommended: include the region name in the VCN's domain label, and include the availability domain name in the subnet's domain label.
In general, the FQDN has a maximum total limit of 63 characters.
The preceding maximums are not enforced when you create the VCN and subnets. However, if the labels exceed the maximum, the Exadata deployment fails.
DNS: Between On-Premises Network and VCN
To enable the use of hostnames when on-premises hosts and VCN resources communicate with each other, you have two options:
Set up an instance in the VCN to be a custom DNS server. For an example of an implementation of this scenario with the Oracle Terraform provider, see Hybrid DNS Configuration.
Manage hostname resolution yourself manually.
Node Access to Object Storage: Static Route
Access to Oracle Cloud Infrastructure Object Storage is required for backing up databases, patching, and updating the cloud tooling on an Exadata DB system. Regardless of how you set up the VCN with that access (for example, with a service gateway), you must configure a static route to Object Storage on each of the compute nodes in the cluster. This is required because, by default, all traffic in an Exadata DB system is routed through the data network. You need the traffic destined for Object Storage to be routed instead through the backup interface (BONDETH1).
You must configure a static route for Object Storage access on each compute node in an Exadata DB system. Otherwise, attempts to back up databases, patch, or update tooling on the system might fail.
Oracle Cloud Infrastructure Object Storage uses the CIDR block IP range 18.104.22.168/17 for all regions. This range was introduced in April and May of 2018.
As of June 1, 2018, Object Storage no longer supports the following discontinued IP ranges. Oracle recommends that you remove these older IP addresses from your access-control lists, firewall rules, and other rules after you have adopted the new IP ranges.
In the task for updating routing, add a route rule to the backup subnet's custom route table. For the destination service, use OCI <region> Object Storage and target = the service gateway.
In the task for updating security rules in the subnet, perform the task on the backup network's network security group (NSG) or custom security list. Set up a security rule with the destination service set to OCI <region> Object Storage. See Rule Required Specifically for the Backup Network.
In the task for updating routing in each subnet, add a rule to each subnet's custom route table. For the destination service, use All <region> Services in Oracle Services Network and target = the service gateway.
In the task for updating security rules for the subnet, perform the task on the backup network's network security group (NSG) or custom security list. Set up a security rule with the destination service set to OCI <region> Object Storage. See Rule Required Specifically for the Backup Network. Note that the client subnet already has a broad egress rule that covers access to the YUM repos.
Here are a few additional details about using the service gateway for option 2:
Both the client subnet and backup subnet use the service gateway, but to access different services. You cannot enable both the OCI <region> Object Storage service CIDR label and the All <region> Services in Oracle Services Network for the service gateway. To cover the needs of both subnets, you must enable All <region> Services in Oracle Services Network for the service gateway. The VCN can have only a single service gateway.
Any route rule that targets a given service gateway must use an enabled service CIDR label and not a CIDR block as the destination for the rule. That means for option 2, the route tables for both subnets must use All <region> Services in Oracle Services Network for their service gateway rules.
Unlike route rules, security rules can use either any service CIDR label (whether the VCN has a service gateway or not) or a CIDR block as the source or destination CIDR for the rule. Therefore, although the backup subnet has a route rule that uses All <region> Services in Oracle Services Network, the subnet can have a security rule that uses OCI <region> Object Storage. See Rule Required Specifically for the Backup Network.
Security Rules for the Exadata System
This section lists the security rules to use with your Exadata system. Security rules control the types of traffic allowed for the client network and backup network of the Exadata's compute nodes. The rules are divided into three sections.
Rules Required for Both the Client Network and Backup Network
This section has several general rules that enable essential connectivity for hosts in the VCN.
If you use security lists to implement your security rules, be aware that the rules that follow are included by default in the default security list. Update or replace the list to meet your particular security needs. The two ICMP rules (general ingress rules 2 and 3) are required for proper functioning of network traffic within the Oracle Cloud Infrastructure environment. Adjust the general ingress rule 1 (the SSH rule) and the general egress rule 1 to allow traffic only to and from hosts that require communication with resources in your VCN.
This rule is for SQL*NET traffic and is required in these cases:
If you need to enable client connections to the database
If you plan to use Oracle Data Guard
Stateless: No (all rules must be stateful)
Source Type: CIDR
Source CIDR: Client subnet's CIDR
IP Protocol: TCP
Source Port Range: All
Destination Port Range: 1521
Description: An optional description of the rule.
The two preceding client ingress rules only cover connections initiated from within the client subnet. If you have a client that resides outside the VCN, Oracle recommends setting up two additional similar rules that instead have the Source CIDR set to the public IP address of the client.
The next four rules (two ingress, two egress) allow TCP and ICMP traffic inside the client network and enable the nodes to communicate with each other. If TCP connectivity fails across the nodes, the Exadata DB system fails to provision.
The following security rule is important for the backup network because it enables the DB system to communicate with Object Storage through the service gateway (and optionally with the Oracle YUM repos if the client network doesn't have access to them). It is redundant with the general egress rule in Rules Required for Both the Client Network and Backup Network (and in the default security list). It is optional but recommended in case the general egress rule (or default security list) is inadvertently changed.
When the database administrator creates the Exadata DB system, they must choose several networking components (for example, which VCN and subnets to use):
When they choose the client subnet, they can also choose which NSG or NSGs to use. Make sure they choose the client network's NSG.
When they choose the backup subnet, they can also choose which NSG or NSGs to use. Make sure they choose the backup network's NSG.
You could instead create a separate NSG for the general rules. Then when the database administrator chooses which NSGs to use for the client network, make sure they choose both the general NSG and the client network NSG. Similarly for the backup network, they choose both the general NSG and the backup network NSG.
The new custom security list you created for the backup subnet.
Later when the database administrator creates the Exadata DB system, they must choose several networking components. When they select the client subnet and backup subnet that you've already created and configured, the security rules are automatically enforced for the nodes created in those subnets.
Do not remove the default egress rule from the default security list. If you do, make sure to instead include the following replacement egress rule in the client subnet's security list: