proxmox-admin

SKILL.md

Proxmox VE Administration

Overview

Proxmox VE is a server virtualization platform built on Debian. It manages KVM virtual machines and LXC containers through a web UI or CLI tools. This skill covers CLI-based administration using qm (VMs), pct (containers), and supporting utilities.

When to Use

Creating, configuring, or managing KVM virtual machines

Spawning and administering LXC containers

Managing Proxmox storage, networking, or clustering

Automating VM/container provisioning via scripts

Troubleshooting Proxmox host or guest issues

Not for: Web UI-only workflows (use the CLI equivalents below).

Quick Reference

Tool
Purpose

qm
Manage KVM virtual machines

pct
Manage LXC containers

pvesm
Manage storage

pvecm
Manage cluster

pveam
Manage appliance/template downloads

pvesh
Access the Proxmox API from the shell

pveperf
Benchmark host performance

VM Management with qm

Creating a VM

# Create a VM with ID 100
qm create 100 --name my-vm --memory 2048 --cores 2 --sockets 1 \
  --net0 virtio,bridge=vmbr0 --ostype l26

# Create with SCSI disk on local-lvm storage (32GB)
qm create 100 --name my-vm --memory 4096 --cores 4 \
  --scsi0 local-lvm:32 --scsihw virtio-scsi-pci \
  --net0 virtio,bridge=vmbr0 --ostype l26

# Attach an ISO for installation
qm set 100 --cdrom local:iso/ubuntu-22.04-server.iso --boot order=ide2

VM Lifecycle

Command
Purpose

qm start <vmid>
Start a VM

qm shutdown <vmid>
Graceful ACPI shutdown

qm stop <vmid>
Force stop (like pulling power)

qm reboot <vmid>
Reboot a VM

qm reset <vmid>
Hard reset

qm suspend <vmid>
Suspend to RAM

qm resume <vmid>
Resume from suspend

qm destroy <vmid>
Delete VM and its disks

qm destroy <vmid> --purge
Delete VM, disks, and all related jobs

VM Configuration

# Show current config
qm config 100

# Modify hardware
qm set 100 --memory 8192
qm set 100 --cores 4
qm set 100 --balloon 2048          # dynamic memory (min)
qm set 100 --cpu cputype=host      # pass through host CPU features
qm set 100 --machine q35           # use Q35 chipset (for PCIe passthrough)

# Add/resize disks
qm set 100 --scsi1 local-lvm:50    # add 50GB disk
qm disk resize 100 scsi0 +20G      # grow existing disk by 20GB

# Networking
qm set 100 --net0 virtio,bridge=vmbr0,tag=10   # VLAN tagged
qm set 100 --net1 virtio,bridge=vmbr1           # second NIC

# Cloud-init (for automated provisioning)
qm set 100 --ide2 local-lvm:cloudinit
qm set 100 --ciuser admin --cipassword 'secret'
qm set 100 --ipconfig0 ip=10.0.0.50/24,gw=10.0.0.1
qm set 100 --sshkeys ~/.ssh/authorized_keys
qm set 100 --boot order=scsi0

# EFI / UEFI boot
qm set 100 --bios ovmf --efidisk0 local-lvm:1,efitype=4m,pre-enrolled-keys=1

# Serial console (headless)
qm set 100 --serial0 socket --vga serial0

# PCI passthrough (GPU, NIC, etc.)
qm set 100 --hostpci0 0000:01:00.0,pcie=1

Snapshots and Cloning

# Create a snapshot
qm snapshot 100 before-upgrade --description "Before kernel upgrade"

# List snapshots
qm listsnapshot 100

# Rollback to snapshot
qm rollback 100 before-upgrade

# Delete a snapshot
qm delsnapshot 100 before-upgrade

# Clone a VM (full copy)
qm clone 100 101 --name cloned-vm --full

# Clone as linked clone (shares base disk, faster)
qm clone 100 101 --name linked-vm

Templates

# Convert VM to template (irreversible)
qm template 100

# Create VM from template (linked clone)
qm clone 100 200 --name from-template

# Create VM from template (full clone)
qm clone 100 200 --name from-template --full

Migration

# Online migration to another node
qm migrate 100 node2 --online

# Offline migration
qm migrate 100 node2

Monitoring

# VM status
qm status 100

# List all VMs
qm list

# Show running processes/agent info
qm agent 100 ping
qm agent 100 get-osinfo

# Monitor interface (QEMU monitor)
qm monitor 100

Container Management with pct

Creating a Container

# Download a template first
pveam update
pveam available --section system
pveam download local debian-12-standard_12.2-1_amd64.tar.zst

# Create container with ID 200
pct create 200 local:vztmpl/debian-12-standard_12.2-1_amd64.tar.zst \
  --hostname my-ct --memory 1024 --cores 2 \
  --rootfs local-lvm:8 \
  --net0 name=eth0,bridge=vmbr0,ip=dhcp \
  --password 'secret' --unprivileged 1

# Create with static IP
pct create 201 local:vztmpl/debian-12-standard_12.2-1_amd64.tar.zst \
  --hostname web-ct --memory 2048 --cores 2 \
  --rootfs local-lvm:16 \
  --net0 name=eth0,bridge=vmbr0,ip=10.0.0.51/24,gw=10.0.0.1 \
  --nameserver 1.1.1.1 --unprivileged 1

Container Lifecycle

Command
Purpose

pct start <ctid>
Start container

pct shutdown <ctid>
Graceful shutdown

pct stop <ctid>
Force stop

pct reboot <ctid>
Reboot container

pct destroy <ctid>
Delete container and its volumes

pct enter <ctid>
Open a shell inside the container

pct exec <ctid> -- <cmd>
Run a command inside the container

pct console <ctid>
Attach to container console

Container Configuration

# Show config
pct config 200

# Modify resources
pct set 200 --memory 4096
pct set 200 --cores 4
pct set 200 --swap 1024

# Add mount point (bind mount from host)
pct set 200 --mp0 /mnt/data,mp=/data

# Add additional storage volume
pct set 200 --mp1 local-lvm:50,mp=/var/lib/data

# Networking
pct set 200 --net0 name=eth0,bridge=vmbr0,ip=10.0.0.60/24,gw=10.0.0.1
pct set 200 --net1 name=eth1,bridge=vmbr1,ip=dhcp

# Features (nesting, FUSE, NFS)
pct set 200 --features nesting=1
pct set 200 --features nesting=1,fuse=1,mount=nfs

# DNS
pct set 200 --nameserver "1.1.1.1 8.8.8.8" --searchdomain example.com

# Start on boot
pct set 200 --onboot 1 --startup order=1,up=30

Container Snapshots and Cloning

# Snapshot
pct snapshot 200 clean-install

# Rollback
pct rollback 200 clean-install

# Clone
pct clone 200 201 --hostname cloned-ct --full

Storage Management

# List storage pools
pvesm status

# List content of a storage
pvesm list local
pvesm list local-lvm

# Add storage (examples)
pvesm add dir my-backup --path /mnt/backup --content backup
pvesm add nfs nfs-share --server 10.0.0.5 --export /exports/pve --content images,vztmpl
pvesm add lvm my-lvm --vgname my-vg --content rootdir,images
pvesm add zfspool my-zfs --pool rpool/data --content rootdir,images

# Remove storage
pvesm remove my-backup

# Download ISO
wget -P /var/lib/vz/template/iso/ https://example.com/image.iso

Networking

# List network interfaces
cat /etc/network/interfaces

# Common bridge configuration (in /etc/network/interfaces)
# auto vmbr0
# iface vmbr0 inet static
#     address 10.0.0.1/24
#     bridge-ports eno1
#     bridge-stp off
#     bridge-fd 0

# Apply network changes
ifreload -a

Cluster Management

# Create a new cluster
pvecm create my-cluster

# Join an existing cluster
pvecm add 10.0.0.1

# Show cluster status
pvecm status

# List cluster nodes
pvecm nodes

# Remove a node (run from a remaining node)
pvecm delnode nodename

# Check quorum
pvecm expected 1    # force quorum (dangerous, single-node recovery only)

Firewall

# Start or stop the node firewall service
pve-firewall start
pve-firewall stop
pve-firewall status

# Enable datacenter firewall in /etc/pve/firewall/cluster.fw
# [OPTIONS]
# enable: 1
#
# Manage rules via config files. Add remote management allow rules before
# enabling restrictive policies.
# Datacenter: /etc/pve/firewall/cluster.fw
# Node:       /etc/pve/nodes/<node>/host.fw
# VM/CT:      /etc/pve/firewall/<vmid>.fw

Backup and Restore

# Backup a VM
vzdump 100 --storage local --mode snapshot --compress zstd

# Backup a container
vzdump 200 --storage local --mode stop --compress zstd

# Backup all guests
vzdump --all --storage local --mode snapshot --compress zstd --mailto admin@example.com

# Restore a VM
qmrestore /var/lib/vz/dump/vzdump-qemu-100-*.vma.zst 100

# Restore a container
pct restore 200 /var/lib/vz/dump/vzdump-lxc-200-*.tar.zst

# Restore to different storage
qmrestore /var/lib/vz/dump/vzdump-qemu-100-*.vma.zst 100 --storage local-lvm

Common Provisioning Patterns

Cloud-Init VM from Template

# 1. Create base VM and install OS, then convert to template
qm template 9000

# 2. Clone and customize with cloud-init
qm clone 9000 110 --name web-server --full
qm set 110 --ciuser deploy --sshkeys ~/.ssh/authorized_keys
qm set 110 --ipconfig0 ip=10.0.0.110/24,gw=10.0.0.1
qm set 110 --nameserver 1.1.1.1
qm start 110

Batch Create Containers

for i in $(seq 1 5); do
  CTID=$((300 + i))
  pct create $CTID local:vztmpl/debian-12-standard_12.2-1_amd64.tar.zst \
    --hostname "worker-${i}" --memory 1024 --cores 2 \
    --rootfs local-lvm:8 \
    --net0 name=eth0,bridge=vmbr0,ip=10.0.0.$((60 + i))/24,gw=10.0.0.1 \
    --unprivileged 1 --start 1
done

Import Disk Image (e.g., cloud image)

# Download a cloud image
wget https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img

# Import to a VM
qm disk import 100 jammy-server-cloudimg-amd64.img local-lvm

# Attach the imported disk
qm set 100 --scsi0 local-lvm:vm-100-disk-0
qm set 100 --boot order=scsi0

Troubleshooting

Problem
Solution

VM won't start
Check qm config <vmid>, verify storage exists with pvesm status

"TASK ERROR: can't lock file"
Check running tasks first; if the task is gone, use qm unlock <vmid> or pct unlock <ctid>

Container has no network
Check bridge exists: brctl show; verify firewall rules

Disk full on storage
pvesm status to check usage; lvs for LVM thin pools

Cluster quorum lost
pvecm expected 1 on surviving node (single-node recovery only)

Migration fails
Ensure same CPU type or use --online with live migration; check network between nodes

Backup fails with lock error
qm unlock <vmid> or pct unlock <ctid>

Slow disk I/O in VM
Use --scsihw virtio-scsi-single and disk options like ,iothread=1,discard=on

Guest agent not responding
Install qemu-guest-agent in the VM and enable: qm set <vmid> --agent 1

Useful Paths

Path
Contents

/etc/pve/
Cluster-wide config (pmxcfs)

/etc/pve/qemu-server/<vmid>.conf
VM configuration files

/etc/pve/lxc/<ctid>.conf
Container configuration files

/etc/pve/storage.cfg
Storage definitions

/etc/pve/nodes/
Per-node configuration

/var/lib/vz/
Default local storage root

/var/lib/vz/template/iso/
ISO images

/var/lib/vz/template/cache/
Container templates

/var/lib/vz/dump/
Backup files

/var/log/pve/tasks/
Task logs