Glossary¶
This glossary provides a quick reference for common Azure Virtual Machine terms and concepts. Refer to these definitions to better understand the Azure compute platform.
| Term | Definition | Related Concept |
|---|---|---|
| ACU | Azure Compute Unit; a way of comparing CPU performance across VM sizes. | VM Size |
| Availability Set | A logical grouping of VMs that ensures they are spread across different hardware racks. | Fault Domain |
| Availability Zone | Physically separate data centers within an Azure region. | SLA |
| Azure Bastion | A service providing secure RDP and SSH access to VMs over SSL. | NSG |
| Azure Backup | A service to back up and restore data from Azure VMs. | Recovery Services vault |
| Boot Diagnostics | A feature that captures the console output and screenshots of a VM during startup. | Troubleshooting |
| Custom Script Extension | A tool to download and run scripts on Azure VMs for post-deployment configuration. | VM Extension |
| Deallocate | Stopping a VM and releasing its hardware resources to avoid compute charges. | Stopped |
| Temporary Disk | A local disk on the host server providing short-term storage; data is lost on stop/deallocate or host maintenance. Not a managed disk. | Ephemeral OS Disk |
| Fault Domain | A group of VMs that share a common power source and network switch. | Availability Set |
| JIT Access | Just-In-Time access; minimizes exposure to attacks by only opening ports when needed. | Defender for Cloud |
| Managed Disk | A disk managed by Azure, simplifying storage account management. | Storage Account |
| Managed Identity | An identity for Azure resources that allows them to authenticate to other services. | Entra ID |
| NSG | Network Security Group; filters network traffic to and from Azure resources. | Firewall |
| NIC | Network Interface Card; enables a VM to communicate with other resources. | VNet |
| OS Disk | The disk containing the operating system for the VM. | Managed Disk |
| Premium SSD | High-performance SSD-based storage for I/O-intensive workloads. | Managed Disk |
| Public IP | An IP address used for communication with resources outside the VNet. | Internet |
| RBAC | Role-Based Access Control; manages access to Azure resources based on roles. | IAM |
| Recovery Services vault | A storage entity in Azure that holds data like backup copies and recovery points. | Azure Backup |
| Redeploy | Moving a VM to a new Azure node to resolve hardware-related issues. | Troubleshooting |
| Reimage | Reinstalling the operating system on a VM disk. | OS Disk |
| Serial Console | A tool providing direct console access to a VM for troubleshooting boot issues. | Boot Diagnostics |
| VMSS | Virtual Machine Scale Sets; allow you to create and manage a group of load-balanced VMs. | Auto-scaling |
| VNet | Virtual Network; the fundamental building block for your private network in Azure. | Subnet |
| Update Domain | A group of VMs that can be rebooted at the same time during platform maintenance. | Availability Set |
| Ultra Disk | The highest performance managed disk type with sub-millisecond latency. | Premium SSD v2 |
graph TD
User([User]) -->|Auth| IAM[RBAC / Managed Identity]
IAM -->|Access| VM[Virtual Machine]
VM --- Storage[Managed Disk / OS Disk / Premium SSD]
VM --- Network[VNet / NIC / NSG / Public IP]
VM --- Availability[Availability Set / Zone / VMSS]
VM --- Management[Backup / Monitoring / Extensions]
Availability --- FD[Fault Domain / Update Domain]Note
A VM in the Stopped (Deallocated) state does not incur compute charges, but you will still be charged for the associated disks and other resources.