to Increase disk performance by using NVMe disks you can use Dense IO Shape also as  the number of CPUs will not change so we should VM.DenseIO2.16

References:

https://docs.cloud.oracle.com/en-us/iaas/Content/Resources/Assets/whitepapers/deploying-c ustom-os-images.pdf

A template of a virtual hard drive that determines the operating system and other software for an instance. For details about Oracle Cloud Infrastructure platform images, see Oracle-Provided Images. You can also launch instances from:

Trusted third-party images published by Oracle partners from the Partner Image catalog. For more information about partner images, see Overview of Marketplace and Working with Listings.

Pre-built Oracle enterprise images and solutions enabled for Oracle Cloud Infrastructure

Custom images, including bring your own image scenarios.

Boot Volumes.

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You can copy objects to other buckets in the same region and to buckets in other regions.

You must have the required access to both the source and destination buckets when performing an object copy. You must also have permissions to manage objects in the source and destination buckets.

Because Object Storage is a regional service, you must authorize the Object Storage service for each region carrying out copy operations on your behalf. For example, you might authorize the Object Storage service in region US East (Ashburn) to manage objects on your behalf. Once you authorize the Object Storage service, you can copy an object stored in a US East (Ashburn) bucket to a bucket in another region.

You can use overwrite rules to control the copying of objects based on their entity tag (ETag) values.

Specify an existing target bucket for the copy request. The copy operation does not automatically create buckets.

With FastConnect, you can choose to use private peering, public peering, or both.

Private peering: To extend your existing infrastructure into a virtual cloud network (VCN) in Oracle Cloud Infrastructure (for example, to implement a hybrid cloud, or a lift and shift scenario). Communication across the connection is with IPv4 private addresses (typically RFC 1918).

Public peering: To access public services in Oracle Cloud Infrastructure without using the internet. For example, Object Storage, the Oracle Cloud Infrastructure Console and APIs, or public load balancers in your VCN. Communication across the connection is with IPv4 public IP addresses. Without FastConnect, the traffic destined for public IP addresses would be routed over the internet.

Database backups can fail for various reasons. Typically, a backup fails because either the database host cannot access the object store, or there are problems on the host or with the database configuration.

First need to determining the Problem

In the Console, a failed database backup either displays a status of Failed or hangs in the Backup in Progress or Creating state. If the error message does not contain enough information to point you to a solution, you can use the database CLI and log files to gather more data. Then, refer to the applicable section in this topic for a solution.

Database Service Agent Issues

Your Oracle Cloud Infrastructure Database makes use of an agent framework to allow you to manage your database through the cloud platform. Occasionally you might need to restart the dcsagent program if it has the status of stop/waiting to resolve a backup failure.

Object Store Connectivity Issues

Backing up your database to Oracle Cloud Infrastructure Object Storage requires that the host can connect to the applicable Swift endpoint. You can test this connectivity by using a Swift user.

Host Issues

One or more of the following conditions on the database host can cause backups to fail:

- Interactive Commands in the Oracle Profile

- The File System Is Full

- Incorrect Version of the Oracle Database Cloud Backup Module

- Changes to the Site Profile File (glogin.sql)

Database Issues

An improper database state or configuration can lead to failed backups.

- Database Not Running During Backup

- Archiving Mode Set to NOARCHIVELOG (When you provision a new database, the archiving mode is set to ARCHIVELOG by default. This is the required archiving mode for backup operations)

- Stuck Database Archiver Process and Backup Failures

- Temporary Tablespace Errors

- RMAN Configuration and Backup Failures

- RMAN Retention Policy and Backup Failures

- Loss of Objectstore Wallet File and Backup Failures

TDE Wallet and Backup Failures

- Incorrect TDE Wallet Location Specification

- Incorrect State of the TDE Wallet

- Incorrect Configuration Related to the TDE Wallet

- Missing TDE Wallet File

As this is not new provisioned database and already in the ARCHIVELOG , regular backups of DB system to OCI object storage in places, so the best answers are,

- Ensure that your database host can connect to the OCI object storage

- Restart the database service agent

A public IP address is an IPv4 address that is reachable from the internet. If a resource in your tenancy needs to be directly reachable from the internet, it must have a public IP address. Depending on the type of resource, there might be other requirements.

There are two types of public IPs:

Ephemeral: Think of it as temporary and existing for the lifetime of the instance.

Reserved: Think of it as persistent and existing beyond the lifetime of the instance it's assigned to. You can unassign it and then reassign it to another instance whenever you like. Exception: reserved public IPs on public load balancers.

To create a new reserved public IP in your pool

Confirm you're viewing the region and compartment where you want to create the reserved public IP.

Open the navigation menu. Under Core Infrastructure, go to Networking and click Public IPs.

Click Create Reserved Public IP.

Enter the following:

Name: An optional friendly name for the reserved public IP. The name doesn't have to be unique, and you can change it later. Avoid entering confidential information.

Compartment: Leave as is.

Tags:Optionally, you can apply tags. If you have permissions to create a resource, you also have permissions to apply free-form tags to that resource. To apply a defined tag, you must have permissions to use the tag namespace. For more information about tagging, see Resource Tags. If you are not sure if you should apply tags, skip this option (you can apply tags later) or ask your administrator.

Click Create Reserved Public IP.

To assign a reserved public IP to a private IP

Prerequisite: The private IP must not have an ephemeral or reserved public IP already assigned to it. If it does, first delete the ephemeral public IP, or unassign the reserved public IP.

Confirm you're viewing the compartment that contains the instance with the private IP you're interested in.

Open the navigation menu. Under Core Infrastructure, go to Compute and click Instances.

Click the instance to view its details.

Under Resources, click Attached VNICs.

The primary VNIC and any secondary VNICs attached to the instance are displayed.

Click the VNIC you're interested in.

Under Resources, click IP Addresses.

The VNIC's primary private IP and any secondary private IPs are displayed.

For the private IP you're interested in, click the Actions icon (three dots), and then click Edit.

In the Public IP Address section, for Public IP Type, select the radio button for Reserved Public IP.

Enter the following:

Compartment: The compartment that contains the reserved public IP you want to assign.

Reserved Public IP: The reserved public IP you want to assign. You have three choices:

Create a new reserved public IP. You may optionally provide a friendly name for it. The name doesn't have to be unique, and you can change it later. Avoid entering confidential information.

Assign a reserved public IP that is currently unassigned.

Move a reserved public IP from another private IP.

Click Update.

VCN1 (10.0.0.0/16) will use the IP Range from 10.0.0.0 to 10.0.255.255 and the VNC 2 (172.16.0.0/16) will use the IP Range from 172.16.0.0 to 172.16.255.255 the will not be overlap between the 2 VCN

in ADW, The tnsnames.ora file provided with the credentials zip file contains three database service names identifiable as high, medium, and low. The predefined service names provide different levels of performance and concurrency for Autonomous Data Warehouse.

high: The High database service provides the highest level of resources to each SQL statement resulting in the highest performance, but supports the fewest number of concurrent SQL statements. Any SQL statement in this service can use all the CPU and IO resources in your database. The number of concurrent SQL statements that can be run in this service is 3, this number is independent of the number of OCPUs in your database.

medium: The Medium database service provides a lower level of resources to each SQL statement potentially resulting a lower level of performance, but supports more concurrent SQL statements. Any SQL statement in this service can use multiple CPU and IO resources in your database. The number of concurrent SQL statements that can be run in this service depends on the number of OCPUs in your database.

low: The Low database service provides the least level of resources to each SQL statement, but supports the most number of concurrent SQL statements. Any SQL statement in this service can use a single CPU and multiple IO resources in your database. The number of concurrent SQL statements that can be run in this service can be up to 300 times the number of OCPUs.

The predefined service names provide different levels of performance and concurrency for Autonomous DB

Choose whichever database service offers the best balance of performance and concurrency.

Use the low database service name. to minimize the impact of their SQLs to by low consumer group

When you create your VCN, you assign a contiguous IPv4 CIDR block of your choice. VCN sizes ranging from /16 (65,533 IP addresses) to /30 (1 IP address) are allowed. Example: 10.0.0.0/16, 192.168.0.0/24.

You can scale up/down your Autonomous Database to scale both in terms of compute (CPU) and storage only when needed, allows people to pay per use.

Oracle allows you to scale compute and storage independently, no need to do it together. these scaling activities fully online (no downtime required)

in Details page Autonomous Database in OCI console, click Scale Up/Down. Click on arrow to select a value for CPU Core Count or Storage (TB).

Or Select auto scaling to allow the system to automatically use up to three times more CPU and IO resources to meet workload demand, compared to the database operating with auto scaling disabled.

References: https://docs.cloud.oracle.com/en-us/iaas/Content/Network/Concepts/fastconnectoverv iew.htm

You use a DRG when connecting your existing on-premises network to your virtual cloud network (VCN) with one (or both) of these:

IPSec VPN

Oracle Cloud Infrastructure FastConnect

You also use a DRG when peering a VCN with a VCN in a different region:

Remote VCN Peering (Across Regions)

References: https://docs.cloud.oracle.com/iaas/Content/DNS/Reference/supporteddnsresource.htm?tocpath=Services%7CDNS%7C_____2

References: https://docs.cloud.oracle.com/iaas/Content/Database/Tasks/migrating.htm

Some of the characteristics and factors to consider when choosing a migration method are:

On-premises database versionDatabase service database versionOn-premises host operating system and versionOn-premises database character setQuantity of data, including indexesData types used in the on-premises databaseStorage for data stagingAcceptable length of system outageNetwork bandwidth

References:

The terraform plan command is used to create an execution plan. Terraform performs a refresh, unless explicitly disabled, and then determines what actions are necessary to achieve the desired state specified in the configuration files.

This command is a convenient way to check whether the execution plan for a set of changes matches your expectations without making any changes to real resources or to the state. For example, terraform plan might be run before committing a change to version control, to create confidence that it will behave as expected.

References: