Virtual Machines (VMs) Explained

Key Concepts

Virtual Machines (VMs) in Oracle Cloud Infrastructure (OCI) are a fundamental compute service that allows you to run multiple operating systems on a single physical server. Understanding VMs involves grasping three key concepts:

• VM Shapes
• Boot Volumes
• Block Volumes

VM Shapes

VM Shapes define the compute, memory, and networking resources allocated to a VM. OCI offers various shapes tailored to different workloads, such as general-purpose, compute-optimized, and memory-optimized shapes. Each shape provides a specific combination of CPU cores, RAM, and network bandwidth.

Example: If you are running a web server that requires high CPU performance, you might choose a compute-optimized shape with more CPU cores. Conversely, if your application is memory-intensive, you would opt for a shape with more RAM.

Boot Volumes

Boot Volumes are block storage devices that contain the operating system and initial software for a VM. Each VM must have a boot volume to start up. Boot volumes are persistent, meaning they retain data even if the VM is stopped or terminated.

Example: When you create a new VM, OCI automatically attaches a boot volume to it. This volume contains the OS (e.g., Linux or Windows) and any initial configurations. If you need to restart the VM, the boot volume ensures that the OS and configurations are preserved.

Block Volumes

Block Volumes provide additional persistent storage for VMs, separate from the boot volume. They can be used for data storage, databases, or any other storage needs. Block volumes can be attached and detached from VMs as needed, providing flexibility and scalability.

Example: Suppose you are running a database on a VM. You might use a block volume to store the database files, ensuring that the data is persistent and can be accessed even if the VM is stopped or restarted. You can also attach additional block volumes to scale storage as your data grows.

Conclusion

Understanding Virtual Machines (VMs) in OCI involves knowing how to choose the right VM shapes for your workload, managing boot volumes for OS and initial configurations, and utilizing block volumes for additional persistent storage. By mastering these concepts, you can effectively deploy and manage VMs to meet your application's needs.