Migrate an On-Premises Oracle Database Deployment to an Autonomous Database

Architecture

This architecture shows the resources and topology required to migrate an on-premises deployment of Oracle Database Enterprise Edition to an Oracle Autonomous Transaction Processing database provisioned on shared Exadata infrastructure in Oracle Cloud.

Description of the illustration migrate-atp.png

The architecture has the following components:

On-premises deployment
The on-premises deployment includes an application server running on a 4-core Intel server and Oracle Database Enterprise Edition on a 16-core Intel server. The database server is connected to a storage device. The on-premises network is connected to an Oracle Cloud region using Oracle Cloud Infrastructure FastConnect or IPSec VPN. The architecture assumes that the on-premises servers are running Oracle Linux.
Region
An Oracle Cloud Infrastructure region is a localized geographic area that contains one or more data centers, called availability domains. Regions are independent of other regions, and vast distances can separate them (across countries or even continents).
Availability domains
Availability domains are standalone, independent data centers within a region. The physical resources in each availability domain are isolated from the resources in the other availability domains, which provides fault tolerance. Availability domains don’t share infrastructure such as power or cooling, or the internal availability domain network. So, a failure at one availability domain is unlikely to affect the other availability domains in the region.
Fault domains
A fault domain is a grouping of hardware and infrastructure within an availability domain. Each availability domain has three fault domains with independent power and hardware. When you distribute resources across multiple fault domains, your applications can tolerate physical server failure, system maintenance, and power failures inside a fault domain.
Virtual cloud network (VCN) and subnets
A VCN is a customizable, software-defined network that you set up in an Oracle Cloud Infrastructure region. Like traditional data center networks, VCNs give you complete control over your network environment. A VCN can have multiple non-overlapping CIDR blocks that you can change after you create the VCN. You can segment a VCN into subnets, which can be scoped to a region or to an availability domain. Each subnet consists of a contiguous range of addresses that don't overlap with the other subnets in the VCN. You can change the size of a subnet after creation. A subnet can be public or private.

In this architecture, the application tier and the Oracle Autonomous Transaction Processing database are isolated in separate private subnets within a single VCN.
Route tables
Virtual route tables contain rules to route traffic from subnets to destinations outside a VCN, typically through gateways.

This architecture uses a route rule to send traffic from the database subnet to Oracle Cloud Infrastructure Object Storage through the service gateway. If you plan to take manual backups of your database, then this rule is required.
Security lists
For each subnet, you can create security rules that specify the source, destination, and type of traffic that must be allowed in and out of the subnet.

This architecture uses ingress and egress rules in the security lists attached to the application server and database subnets. These rules enable connectivity between the application and database. Ingress rules are temporarily added in the security lists attached to the application server and database server subnets during migration, for transferring application files, shell scripts, and configuration data.
Dynamic routing gateway (DRG)
The DRG is a virtual router that provides a path for private network traffic between a VCN and a network outside the region, such as a VCN in another Oracle Cloud Infrastructure region, an on-premises network, or a network in another cloud provider.
Service gateway
The service gateway provides access from a VCN to other services, such as Oracle Cloud Infrastructure Object Storage. The traffic from the VCN to the Oracle service travels over the Oracle network fabric and never traverses the internet.
Block volume
With block storage volumes, you can create, attach, connect, and move storage volumes, and change volume performance to meet your storage, performance, and application requirements. After you attach and connect a volume to an instance, you can use the volume like a regular hard drive. You can also disconnect a volume and attach it to another instance without losing data.
Object storage
Object storage provides quick access to large amounts of structured and unstructured data of any content type, including database backups, analytic data, and rich content such as images and videos. Use standard storage for "hot" storage that you need to access quickly, immediately, and frequently. Use archive storage for "cold" storage that you retain for long periods of time and seldom or rarely access.
Database system
The on-premises database is migrated to a 16-core Oracle Autonomous Transaction Processing database provisioned on shared Exadata infrastructure.
Application server
The on-premises application server is migrated to a 4-core compute instance.

Recommendations

Your requirements might differ from the architecture described here. Use the following recommendations as a starting point.

Compute shapes
This architecture uses an Oracle Linux compute instance with a VM.Standard2.4 shape for the application server. If the application needs more processing power, memory, or network bandwidth, then choose a larger shape.
Block volumes
This architecture uses a 100-GB block volume for the application server. You can use the volume for installing the application, or to store application logs and data.
Database
This architecture uses an Oracle Autonomous Transaction Processing database on shared Exadata infrastructure, with 16 cores enabled at provisioning time. You can enable autoscaling to give the database workloads up to three times the processing power.

If you need self-service capability within a private database environment running in the public cloud, consider using Oracle Autonomous Transaction Processing on dedicated Exadata infrastructure.
VCN
When you create a VCN, determine the number of CIDR blocks required and the size of each block based on the number of resources that you plan to attach to subnets in the VCN. Use CIDR blocks that are within the standard private IP address space.

Select an address range that doesn’t overlap with your on-premises network, so that you can set up a connection between the VCN and your on-premises network using Oracle Cloud Infrastructure FastConnect or IPSec VPN.

After you create a VCN, you can change, add, and remove its CIDR blocks.

When you design the subnets, consider your traffic flow and security requirements. Attach all the resources within a specific tier or role to the same subnet, which can serve as a security boundary.

Use separate regional private subnets for the application tier and the database.
Database migration method
In this reference architecture, the Move to Autonomous Database (MV2ADB) tool is used to migrate data from an on-premises Oracle Database Enterprise Edition deployment to an Oracle Autonomous Transaction Processing database.

MV2ADB uses Oracle Data Pump. A single command (mv2adb auto) exports data from the specified source database to Oracle Cloud Infrastructure Object Storage, and then loads the data to the Oracle Autonomous Transaction Processing database.
The following are the prerequisites to use MV2ADB:
- HTTP connectivity between your on-premises data center and Oracle Cloud Infrastructure Object Storage.
- SQL*Net connectivity between the on-premises data center and the Oracle Autonomous Transaction Processing database. Consider using Oracle Cloud Infrastructure FastConnect or IPSec VPN.
- The client credentials wallet for the Oracle Autonomous Transaction Processing database. Download the wallet and copy it to the source database server.
- The following tools and utilities on the source database server:
  - The latest version of Oracle Instant Client.
  - The latest version of the Oracle Cloud Infrastructure CLI.
  - The java executable. Make sure that the path is specified in the user's PATH variable.
  - Perl release 5.10 or higher.
  - The Perl Data::Dumper module.
Here's an overview of the data migration process:
1. You first create a bucket in Oracle Cloud Infrastructure Object Storage by using either mv2adb createbucket, the Oracle Cloud Infrastructure CLI, or any other interface.
2. Then, you load the data to Oracle Autonomous Transaction Processing database by using the mv2adb auto command.
  The command performs the following tasks:
  1. Exports data from the source database (schema-based).
  2. Uploads the dump files to the specified bucket in Oracle Cloud Infrastructure Object Storage.
  3. Imports data from Oracle Cloud Infrastructure Object Storage to the Oracle Autonomous Transaction Processing database.
  If required, you can perform these tasks individually, by using the mv2adb operations expdp, putdump, and impdp, respectively as shown in the architecture diagram.
  
  Note:
  To minimize the time required to migrate data from large databases, use Oracle Cloud Infrastructure FastConnect.

Considerations

Scalability
- Application tier:
  You can scale the application server vertically by changing the shape of the compute instance. A shape with a higher core count provides more memory and network bandwidth as well. If more storage is required, increase the size of the block volumes attached to the application server.
- Database tier
  You can scale the database vertically by enabling additional cores for the Oracle Autonomous Transaction Processing database. Both the cores and storage can be scaled up without any database downtime.
Availability
Fault domains provide the best resilience for workloads deployed within a single availability domain. This architecture doesn’t show redundant resources, because the focus is on the migration approach. For high availability in the application tier, deploy the application servers in different fault domains, and use a load balancer to distribute client traffic across the application servers.

The Oracle Autonomous Transaction Processing database provides high availability for the database tier.
Cost
- Application tier
  Select the compute shape based on the cores, memory, and network bandwidth that your application needs. You can start with a 4-core shape for the application server. If you need more performance, memory, or network bandwidth, you can change to a larger shape.
- Database tier
  For Oracle Autonomous Transaction Processing with shared Exadata infrastructure, the CPU and storage usage are billed by the second.
  
  You can either pay for the required database licenses or bring your own licenses (BYOL).

Deploy

To deploy this reference architecture, create the required resources in Oracle Cloud Infrastructure, and then copy data from the on-premises database by using the MV2ADB tool.

Create the required resources in Oracle Cloud Infrastructure.
The Terraform code to deploy the resources in the cloud is available on GitHub. Use the code to provision the required networking resources, a compute instance that you can use as the bastion or for the application server, and an Oracle Autonomous Transaction Processing database.

You can pull the code into Oracle Cloud Infrastructure Resource Manager with a single click, create the stack, and deploy it. Alternatively, download the code from GitHub to your computer, customize the code, and deploy the architecture by using the Terraform CLI.
- Deploy by using Oracle Cloud Infrastructure Resource Manager:
  1. Click
    If you aren't already signed in, enter the tenancy and user credentials.
  2. Review and accept the terms and conditions.
  3. Select the region where you want to deploy the stack.
  4. Follow the on-screen prompts and instructions to create the stack.
  5. After creating the stack, click Terraform Actions, and select Plan.
  6. Wait for the job to be completed, and review the plan.
    To make any changes, return to the Stack Details page, click Edit Stack, and make the required changes. Then, run the Plan action again.
  7. If no further changes are necessary, return to the Stack Details page, click Terraform Actions, and select Apply.
- Deploy by using the Terraform CLI:
  1. Go to GitHub.
  2. Download the code to your local computer.
  3. Complete the prerequisite steps described in the README.
  4. Apply the configuration using the Terraform CLI.
Migrate the on-premises database using the MV2ADB tool.
Follow the instructions in Oracle Support Document 2463574.1.

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Change Log

This log lists only the significant changes:

November 19, 2020

Added steps to deploy the cloud resources by using Oracle Cloud Infrastructure Resource Manager.