Instance

In terms of Oracle Cloud Infrastructure (OCI), an Instance is a virtual server (virtual machine) that runs in the cloud using the physical servers provided by Oracle.

It provides the compute resources required to run applications, websites, databases, and other workloads.

Simple Explanation

Think of an Instance as a computer/server in the cloud.

Instead of purchasing and maintaining a physical server in your own data center, you can create an instance in OCI and use its resources remotely.

An OCI Instance Provides

• CPU – to process tasks
• Memory (RAM) – to run applications
• Storage – to store the operating system, applications, and data
• Operating System – such as Linux or Windows
• Network connectivity – to communicate with other resources and the Internet

Steps to create an Instance in OCI

Step 1 - Click on the Burger menu/Nevegation menu

Step 2 - Click on Compute and then Instances

Step 3 - Select the correct compartment to create an Instance

Step 4 - Click on Create instance

Step 5 - Give the instance a name and select the compute service compartment

Step 6 - In the Placement section, choose any one availability domain

Step 7 - Click on Advanced options and select the preferred capacity type

• Note: Industry preference - "On-demand capacity" We pay only for services we use

Step 8 - Select a Fault Domain or leave it for OCI to choose the right FD for the instance

Meaning of Image and Shape Category in OCI

• Image: OS (operating system) of the server.
• Shape: Hardware resources/processor allocated to an instance.

Step 9 - Click Change image icon

Step 10 - On the Select an image page, select an OS and its version (the second-latest version is always recommended) and then click Select image

Step 11 - Click Change shape

Step 12 - On Browse all shapes page select Instance type and Shape series (AMD recommended)

Step 12 - Configure hardware resources and Click Expand button

Step 13 - Select the shape build (Number of OCPUs and Amount of memory (GB)), then click Select shape

Step 14 - Click Next

Step 15 - Click Next

Step 16 - On the Networking page, under Primary network, choose Select existing virtual cloud network and inside the Virtual cloud network compartment, select the network service compartment. It will automatically select the VCN from that network service compartment

Step 17 - For Subnet selection, select the network service compartment for the Subnet compartment and then in the Subnet selection dropdown, select Public subnet

Step 18 - Inside Private IPv4 address assignment and Private IPv4 address assignment select Automatically assign

Step 19 - Add SSH keys

• To connect to the instance, we need both the SSH key pair public key and private key (asymmetric keys: different from each other)
• The first time we create an instance, we generate a key pair and download it in .pem (Privacy-Enhanced Mail) format, but when trying to login, we need .ppk (PuTTY Private Key) format of the key.

Note:- Next time while creating instance we can use same key pair by choosing second option

Step 20 - Click Next

Step 21 - On the Storage page, we need to do nothing and click Next

Step 22 - Review all the details and click Create