Virtualization, Servers and Storage : How-to list all Virtual Machines with Snapshots

Managing virtual machine (VM) snapshots is a critical part of maintaining and troubleshooting VMs in the University of Toronto's ITS Private Cloud. Snapshots allow you to capture the state of a VM at a specific point in time, which is invaluable for upgrades, testing, and recovery. This guide will show you how to list all VMs with snapshots, using the vss-cli tool, and how to retrieve detailed snapshot information.

Prerequisites

• vss-cli installed: Ensure you have the vss-cli or access to the web interface installed or ssh access to vsscli-demo.eis.utoronto.ca, and configured with your credentials.

• Access permissions: You must have permission to view VMs and snapshots in the target folder.

Quick Command: List VMs with Snapshots

To list all VMs in the Systems folder that have at least one snapshot, use:

vss-cli compute vm ls -f has_snapshot=1 -f folder.path=Systems

• -f has_snapshot=1: Filters for VMs that have snapshots.

• -f folder.path=Systems: Restricts results to VMs in the "Systems" folder.

You can add --columns to customize the output, e.g.:

vss-cli --columns moref,name,folder.path compute vm ls -f has_snapshot=1 -f folder.path=Systems

Script: List VMs and Their Snapshots (with Details)

For a more detailed report—including snapshot IDs and metadata—use the following script:

#!/bin/bash
set -euo pipefail

# List VMs with snapshot in the Systems folder
vss-cli --no-headers --columns moref --table-format plain \
    compute vm ls -f has_snapshot=1 -f folder.path=Systems -s power_state |
while read -r vm; do
    # List snapshot IDs for each VM
    vss-cli --no-headers --columns id --table-format plain \
        compute vm get "$vm" snapshot |
    while read -r snap_id; do
        # Validate that snap_id is a number (integer)
        if [[ "$snap_id" =~ ^[0-9]+$ ]]; then
            echo "VM: $vm | Snapshot ID: $snap_id"
            vss-cli --columns create_time,age,size_gb,name \
                compute vm get "$vm" snapshot "$snap_id"
        else
            echo "Warning: Snapshot ID '$snap_id' for VM '$vm' is not a valid number. Skipping." >&2
        fi
    done
done

What This Script Does

• Step 1: Lists all VMs in the "Systems" folder with snapshots.

• Step 2: For each VM, lists all snapshot IDs.

• Step 3: For each snapshot, prints details: creation time, age, size, and name.

• Step 4: Skips any invalid snapshot IDs (should not occur, but is a safety check).

Understanding the Output

• VM: The Managed Object Reference (moref) of the VM.

• Snapshot ID: Unique identifier for each snapshot.

• Details: Creation time, age (how long the snapshot has existed), size in GB, and the snapshot name.

Best Practices & Notes

• Snapshot Management: Snapshots are not backups; they are delta files tracking changes. Too many or old snapshots can degrade performance and consume excessive storage.

• Snapshot Lifecycle: Snapshots have a start and end date. You can extend their lifetime (up to 72 hours, three times), revert to them, or delete them as needed.

• Consolidation: After deleting snapshots, disk consolidation may be required to reclaim space and improve performance.

• Permissions: If you see errors or missing VMs, check your folder permissions.

Troubleshooting

• No Results? Double-check the folder path and your permissions.

• Invalid Snapshot IDs? This is rare; the script will warn you if it encounters any.

• Performance: For large environments, consider adding pagination or limiting results with -c <count>.

Further Reading

• Snapshot Management

• ITS Private Cloud CLI (vss-cli) Cheat Sheet

• Manage virtual machine snapshots

Summary Table

If you need help with advanced filtering, custom columns, or troubleshooting, reach out to ITS Private Cloud support via https://utor.cloud/help or consult the vss-cli documentation.