The Oracle Zero Downtime Migration service host is installed on a separate, on-premises virtual machine (VM) next to the source database. The target Oracle Exadata Database Service is provisioned in Google Cloud’s data center within Google’s Virtual Private Cloud (VPC). The on-premises data center is connected to Google Cloud by using Google Cloud Interconnect or site-to-site VPN. The Oracle Zero Downtime Migration workflow uses direct data transfer and creates the target database by using the Restore From a Service method, eliminating the need to back up the source database to an intermediate storage location. Oracle Zero Downtime Migration uses Oracle Data Guard to replicate the data from the on-premises database to the target database. Oracle Zero Downtime Migration sets up Oracle Data Guard, maintains it, and cleans up the configuration after the migration completes, so you don't have to. After the migration is complete, the target database can use the Automatic Backup feature to back up the database into Oracle Database Autonomous Recovery Service.

The following diagram illustrates the architecture:

oracle_database_at_google_cloud_w_zdm-oracle.zip

The architecture has the following on-premises and Oracle Cloud Infrastructure components:

• On-premises network

  This network is the local network used by your organization. It is one of the spokes of the topology.

• 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).

• 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 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.

• Route table

  Virtual route tables contain rules to route traffic from subnets to destinations outside a VCN, typically through gateways.

• Security list

  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.

• Site-to-Site VPN

  Site-to-Site VPN provides IPSec VPN connectivity between your on-premises network and VCNs in Oracle Cloud Infrastructure. The IPSec protocol suite encrypts IP traffic before the packets are transferred from the source to the destination and decrypts the traffic when it arrives.

• Oracle Exadata Database Service

  Oracle Exadata Database Service enables you to leverage the power of Exadata in the cloud. Oracle Exadata Database Service delivers proven Oracle Database capabilities on purpose-built, optimized Oracle Exadata infrastructure in the public cloud. Built-in cloud automation, elastic resource scaling, security, and fast performance for all Oracle Database workloads helps you simplify management and reduce costs.

  Oracle Exadata Database Service on Dedicated Infrastructure provides Oracle Exadata Database Machine as a service in an Oracle Cloud Infrastructure (OCI) data center. The Oracle Exadata Database Service on Dedicated Infrastructure instance is a virtual machine (VM) cluster that resides on Exadata racks in an OCI region.

• Oracle Database Autonomous Recovery Service

  Oracle Database Autonomous Recovery Service is an Oracle Cloud service that protects Oracle databases. With backup automation and enhanced data protection capabilities for OCI databases, you can offload all backup processing and storage requirements to Oracle Database Autonomous Recovery Service, thereby eliminating backup infrastructure costs and manual administration overhead.

• Oracle Database@Google Cloud

  Oracle Database@Google Cloud is an Oracle Cloud database service that runs Oracle Database workloads in your Google Cloud environment. All hardware for Oracle Database@Google Cloud is colocated in Google Cloud's data centers and uses Google Cloud networking. The service benefits from the simplicity, security, and low latency of a single operating environment within Google Cloud. You can manage the service on the Google Cloud console or by using Google Cloud automation tools. Google Cloud IAM and Admin provide federated identity and access management for Oracle Exadata Database Service.

• Oracle Cloud Infrastructure Vault

  Oracle Cloud Infrastructure Vault enables you to centrally manage the encryption keys that protect your data and the secret credentials that you use to secure access to your resources in the cloud. You can use the Vault service to create and manage vaults, keys, and secrets.

• Zero Downtime Migration service host

  The Oracle Zero Downtime Migration service host should be a dedicated system but can be shared for other purposes.

  Oracle Zero Downtime Migration software requires a standalone Oracle Linux host running on either Oracle Linux 7 or 8 or Red Hat Enterprise Linux 8 or 9.

  The Oracle Zero Downtime Migration service host must be able to connect to the source and the target database servers; if connectivity is guaranteed, the service host can be located anywhere.

• Data Guard

  Oracle Data Guard and Oracle Active Data Guard provide a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases and that enable production Oracle databases to remain available without interruption. Oracle Data Guard maintains these standby databases as copies of the production database by using in-memory replication. If the production database becomes unavailable due to a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Oracle Active Data Guard provides the additional ability to offload read-mostly workloads to standby databases and also provides advanced data protection features.

The architecture has the following Google components:

• Google Cloud Region

  A Google Cloud region is a geographical area that contains data centers and infrastructure for hosting resources. It is made up of zones that are isolated from each other within the region.

• Google Cloud Project

  A Google Cloud Project is required to use Google Workspace APIs and to build Google Workspace add-ons or apps. A project forms the basis for creating, enabling, and using all Google Cloud services, including managing APIs, enabling billing, adding and removing collaborators, and managing permissions.

• Google Virtual Private Cloud

  Google Cloud Virtual Private Cloud (VPC) provides networking functionality to Compute Engine virtual machine (VM) instances, Google Kubernetes Engine (GKE) containers, database services, and serverless workloads. VPC provides global, scalable, and flexible networking for your cloud-based service.

• Google Cloud Interconnect

  Cloud Interconnect extends your on-premises network to the Google network through a highly available, low-latency connection. Use Dedicated Interconnect to connect directly to Google or use Partner Interconnect to connect to Google through a supported service provider.

• Google Cloud Router

  Cloud Router is a distributed and fully managed service that provides Border Gateway Protocol (BGP) speaker and responder capabilities. Cloud Router works with Cloud Interconnect, Cloud VPN, and Router appliances to create dynamic routes in VPC networks based on BGP-received and custom-learned routes.

Use the following Oracle Zero Downtime Migration (ZDM) workflows to migrate your Oracle Database to Oracle Exadata Database Service on Oracle Database@Google Cloud.

• Physical Online Migration

  The physical online migration workflow supports migrations between the same database versions and platforms. It uses direct data transfer and the restore from service method to create the target database, explicitly avoiding backing up the source database to an intermediate storage location. Oracle Data Guard keeps the source and target databases synchronized to achieve a minimal downtime migration.

• Physical Offline Migration

  The physical offline migration workflow supports migrations between the same database versions and platforms. It creates the target database using Recovery Manager (RMAN) backup and restore. Google Cloud Managed NFS Server provides an NFS file share to store the RMAN backup files.

Use the following ZDM workflows to migrate your Oracle Database to either Oracle Exadata Database Service on Oracle Database@Google Cloud or to Oracle Autonomous Database Serverless on Oracle Database@Google Cloud.

• Logical Online Migration

  The logical online migration workflow supports migrations between the same and different database versions and platforms. It uses Oracle Data Pump export and import to create the target database. Google Cloud Managed NFS Server provides an NFS file share to store the Data Pump dump files. Oracle GoldenGate keeps the source and target databases synchronized to achieve a minimal downtime migration.

• Logical Offline Migration

  The logical offline migration workflow supports migrations between the same and different database versions and platforms. It uses Oracle Data Pump export and import to create the target database. Google Cloud Managed NFS Server provides an NFS file share to store the Data Pump dump files.

• Download the latest Oracle Zero Downtime Migration software version from My Oracle Support (MOS) by searching for patch number 33509650 in the Patches & Updates (see the Deploy section).
• Install the Oracle Zero Downtime Migration service host on premises next to your source database.
• Ensure the Oracle Zero Downtime Migration service host has at least 100GB of free storage.
• Ensure secure and private network connectivity between on-premises and Google Cloud by using site-to-site VPN or Google Cloud Interconnect.
• Depending on your database size, ensure sufficient network throughput from your on-premises network to Google Cloud.

Consider the following points when deploying this reference architecture.

• For Oracle Database 12c Release 2 and later, the TDE wallet must exist on the source, and the wallet status must be in the OPEN state. The source database does not necessarily need to be encrypted, but a TDE wallet must be configured.
• Oracle Zero Downtime Migration requires the SSH key on the Oracle Zero Downtime Migration service host to be in RSA format (in Oracle Linux 8, the default is OPENSSH).
• The target database must:
  • Be provisioned using Oracle Cloud tooling without enabling automatic backups
  • Have a time zone file version that is the same or higher than the source database
• The source and target databases must:
  • Have the same database name (DB_NAME)
  • Have different database unique names (DB_UNIQUE_NAME)
  • Use a server parameter file (SPFILE)
  • Use the same character set
  • Have the same encryption algorithm defined in the sqlnet.ora file
  • The SYS user account password must be the same on the source and target databases
  • The COMPATIBLE database initialization parameter must be the same on the source and target databases
  • The source and target databases could have the same major release version (for example, 19c). However, the target database could have a higher patch level (for example, source at 19.23 and target at 19.24). If the target database is at a higher patch level than the source database, Oracle Zero Downtime Migration automatically runs a data patch as part of the migration. This is configurable and customers migrating within the same version and patch levels can request ZDM to not run data patch.

Download and install the latest Oracle Zero Downtime Migration on-premises next to your source database:

1. Go to My Oracle Support (MOS).
2. To search for the latest ZDM software, select Patch Name or Number, enter the patch number 33509650, and click Search.
3. Click the latest patch number and select Download from the menu.
4. Follow the instructions included in the download.

Learn more about the features of this architecture and about related architectures.

• Migrate Oracle Databases to ExaDB-D on Oracle Database@Google Cloud with Zero Downtime Migration (Video)
• Oracle Zero Downtime Migration
• Oracle Data Guard
• Oracle Database@Google Cloud
• Oracle Cloud Infrastructure Multicloud

Learn about the different Oracle Zero Downtime Migration workflows:

• Physical Online Migration to ExaDB-D on Oracle Database@Google Cloud
• Physical Offline Migration to ExaDB-D on Oracle Database@Google Cloud
• Logical Online Migration to ExaDB-D on Oracle Database@Google Cloud
• Logical Offline Migration to ExaDB-D on Oracle Database@Google Cloud
• Logical Online Migration to ADB-S on Oracle Database@Google Cloud
• Logical Offline Migration to ADB-S on Oracle Database@Google Cloud

Review these additional resources:

• Well-architected framework for Oracle Cloud Infrastructure

• Oracle Cloud Infrastructure Documentation

• Oracle Cloud Cost Estimator

• Authors: Ricardo Gonzalez, Sinan Petrus Toma
• Contributors: Thomas Van Buggenhout, Robert Lies