How to Use the Command 'qm listsnapshot' (with examples)

The qm listsnapshot command is a tool designed to interact with Proxmox Virtual Environment (PVE), a server virtualization management platform. This command is specifically used to list all snapshots of virtual machines (VMs) that reside within a Proxmox VE cluster. A snapshot in virtualization is a point-in-time copy of a VM’s state, including the virtual disk, memory, and other settings, which allows users to revert to that state at any time, useful for testing, backup, and recovery purposes. The ability to list and manage these snapshots is crucial for maintaining control over the virtual environments and ensuring efficient resource management and recovery options.

Use case 1: List all snapshots of a specific virtual machine

Code:

qm listsnapshot 101

Motivation:

Listing all snapshots for a specific virtual machine is often necessary for administrators to have an overview of the available backup points. This information can be integral for tasks such as rolling back to a previous state due to system failure, testing software updates, and confirming the completion of automated backup tasks. It provides insights into the VM’s backup strategy and historical data points, which is important for both disaster recovery and general maintenance. By knowing precisely what snapshots exist, administrators can make better-informed decisions regarding which snapshots to retain or delete, thus optimizing storage resources.

Explanation:

• qm: This is the command-line interface utility in Proxmox for managing virtual machines. It stands for “Qemu/KVM” (quick emulation), which is the virtualization technology Proxmox uses.
• listsnapshot: This is the command option that instructs qm to list all snapshots available for a specified virtual machine.
• 101: This is the unique identifier (ID) of the virtual machine for which snapshots need to be listed. In Proxmox, each VM has a specific ID that is used to manage and reference its resources and actions.

Example output:

Current  Name                       Description
-        initial_setup              Initial setup after OS installation
        - backup_june               Before June monthly update
        - backup_july               Before July monthly update
        - pre_critical_patch        Before applying system-critical security patch

This example output shows a series of snapshots for VM with ID 101. Each snapshot is listed with its name and a brief description, giving the administrator a clear timeline and purpose for each snapshot. The “Current” row indicates which snapshot is currently active or in use.