ProxmoxBackupClientPBSClientTool/BACKUP-TYPES-GUIDE.md

Backup Types and VM Conversion Guide

Three Backup Strategies

When running the installer, you'll be asked to choose between three backup types:

1. File-level Only (.pxar)

What it does: Backs up files and directories as archives

Pros:

• Very fast backups (uses metadata change detection)
• Excellent deduplication (20-40x typical)
• Small backup size
• Selective file restoration
• Perfect for daily backups

Cons:

• Cannot be directly booted as a VM
• Requires manual steps to restore to bare metal
• Need to reinstall bootloader after restore

Best for:

• File recovery
• Configuration backups
• User data protection
• Systems where you just need files, not full disaster recovery

Example use case: Backing up a development laptop where you mainly care about code and configs

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2. Block Device Only (.img)

What it does: Creates full disk/partition images

Pros:

• Directly bootable as a VM - just restore to VM disk and start
• Bare metal restore with dd
• Complete system snapshot (including bootloader, partitions, etc.)
• No post-restore configuration needed
• Perfect for disaster recovery

Cons:

• Much larger backups (backs up entire disk including empty space)
• Slower backup process
• Less deduplication
• More storage required on PBS

Best for:

• Disaster recovery
• Converting physical machines to VMs
• Hardware migration
• Systems you want to boot as VMs later

Example use case: Production laptop you want to be able to boot as a VM in Proxmox if hardware fails

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3. Both (Hybrid) - RECOMMENDED

What it does: Daily file-level backups + Weekly block device backups

How it works:

• File-level backup runs on your schedule (e.g., daily at 2 AM)
• Block device backup runs every Sunday regardless of your schedule
• Both stored in the same datastore

Pros:

• Best of both worlds
• Fast daily backups for file recovery
• Weekly bootable snapshots for disaster recovery
• Reasonable storage usage
• Maximum flexibility

Cons:

• More complex
• Requires more storage than file-only
• Block device backups take longer when they run

Best for:

• Production systems
• Critical laptops/workstations
• Any system where both file recovery AND disaster recovery matter

Example use case: Your main work laptop - daily backups protect recent work, weekly images let you boot as VM if laptop dies

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Storage Requirements Comparison

Example: 256GB laptop with 120GB used space

Backup Type	First Backup	Subsequent Backups	Weekly Storage Growth
File-level	~120GB	~1-5GB (changed files only)	~7-35GB
Block device	~256GB	~256GB each time	~256GB
Both (Hybrid)	~376GB	~1-5GB daily, +256GB Sunday	~263-291GB

Note: Deduplication dramatically reduces actual storage - PBS typically achieves 10-40x deduplication on file-level backups.

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Converting to VMs

File-level Backups → VM

NOT RECOMMENDED - Requires manual work:

1. Create new VM with blank disk
2. Install minimal OS in VM
3. Boot VM into rescue mode
4. Restore .pxar backup over the minimal install
5. Reinstall bootloader (grub-install)
6. Fix /etc/fstab for new disk UUIDs
7. Configure network for VM environment
8. Reboot and troubleshoot

Complexity: High
Success rate: ~60-70%
Time: 1-3 hours

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Block Device Backups → VM

RECOMMENDED - Almost automatic:

# On Proxmox VE host (must have PBS client installed)

# 1. List available backups
proxmox-backup-client snapshot list

# 2. Create VM shell (via GUI or CLI)
qm create 999 --name "laptop-vm" --memory 4096 --cores 2

# 3. Create disk for VM (size >= original disk)
qm set 999 --scsi0 local-lvm:32

# 4. Find VM disk device
VM_DISK=$(lvdisplay | grep "vm-999-disk-0" | awk '{print $3}')
# Or typically: /dev/pve/vm-999-disk-0

# 5. Restore backup directly to VM disk
# Replace sda.img with your actual backup name (e.g., nvme0n1.img)
proxmox-backup-client restore \
  host/your-laptop/2025-11-01T03:00:00Z \
  sda.img \
  "$VM_DISK"

# 6. Configure VM boot
qm set 999 --boot order=scsi0

# 7. Start VM
qm start 999

Complexity: Low
Success rate: ~95%+
Time: 10-30 minutes (mostly waiting for restore)

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Post-VM-Conversion Tasks

After booting the restored laptop as a VM, you'll likely need to:

# 1. Fix network (VM uses virtio, laptop had different interface)
# Ubuntu/Debian:
sudo nano /etc/netplan/01-netcfg.yaml
# Change interface name to ens18 or whatever shows in 'ip a'

# Arch:
sudo nano /etc/systemd/network/20-wired.network

# 2. Install QEMU guest agent (highly recommended)
sudo apt install qemu-guest-agent        # Ubuntu/Debian
sudo pacman -S qemu-guest-agent          # Arch
sudo systemctl enable --now qemu-guest-agent

# 3. Remove laptop-specific packages (optional)
sudo apt remove laptop-mode-tools tlp   # Power management
sudo pacman -Rs laptop-mode-tools

# 4. Update fstab if needed (usually not required)
# Only if you see errors about missing disks

# 5. Reboot to ensure everything works
sudo reboot

That's it! Your laptop is now running as a VM.

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Bare Metal Restoration (New Laptop/Hardware)

Scenario: Laptop died, bought new one with bigger SSD

Using Block Device Backup:

1. Boot new laptop from Ubuntu/Arch USB
2. Install PBS client on live system
3. Configure connection to your PBS
4. List backups and find latest
5. Restore directly to new disk:

# On live USB system
sudo apt install proxmox-backup-client  # or yay -S on Arch

# Configure (temporary)
export PBS_REPOSITORY='user@pbs!token@192.168.1.181:8007:backups'
export PBS_PASSWORD='your-token-secret'

# List backups
proxmox-backup-client snapshot list

# Restore to new disk (replace /dev/nvme0n1 with your new disk)
proxmox-backup-client restore \
  host/old-laptop/2025-11-01T03:00:00Z \
  sda.img \
  /dev/nvme0n1

# Reboot
sudo reboot

6. Remove USB, boot from restored disk
7. System should boot normally with all your data

If new disk is larger: The restored partition will be original size. Expand it:

# After first boot from restored disk

# For ext4 filesystem
sudo growpart /dev/nvme0n1 1  # Expand partition
sudo resize2fs /dev/nvme0n1p1  # Expand filesystem

# For btrfs
sudo btrfs filesystem resize max /

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Which Should You Choose?

Choose File-level only if:

• Storage on PBS is very limited
• You only care about recovering files, not full system
• You're comfortable reinstalling OS if hardware fails
• Backup speed is critical

Choose Block device only if:

• You specifically want VM conversion capability
• Storage space is not a concern
• You rarely backup (weekly/monthly)
• System rarely changes

Choose Both (Hybrid) if:

• You want maximum protection
• PBS has decent storage (500GB+ free)
• System is important/production
• You want both fast recovery AND disaster recovery options
• This is the recommended default

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Storage Planning

For Hybrid Backups

Calculate required PBS storage:

Initial: (Disk Size) + (Used Space)
Weekly: + (Disk Size)
Monthly: 4 × (Disk Size) + ~(Used Space × 2)

Example: 512GB laptop with 200GB used

Initial: 512GB + 200GB = 712GB
After 1 month: 512 + 200 + (4 × 512) + 400 = 2860GB ≈ 3TB
With dedup: ~1TB actual storage (typical 3:1 compression)

Recommendation: PBS datastore with at least 3x your total disk size for comfortable monthly retention with hybrid backups.

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Testing Your Backups

CRITICAL: Always test restores before you need them!

Test File-level Restore

# Restore single file to verify
proxmox-backup-client restore \
  host/laptop/2025-11-01T03:00:00Z \
  root.pxar /tmp/test-restore \
  --pattern 'etc/hostname'

cat /tmp/test-restore/etc/hostname

Test Block Device Restore

# On Proxmox VE, create test VM quarterly
# Follow VM conversion steps above
# Verify VM boots successfully
# Delete test VM after verification

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Troubleshooting

Block device backup fails: "cannot open device"

Problem: Device is busy/mounted

Solution:

# Option 1: Backup while system is running (works, but not ideal)
# Current script does this - it's safe but may have minor inconsistencies

# Option 2: Boot from USB and backup unmounted disk (best)
# Boot from Live USB
# Install PBS client
# Backup the unmounted disk

VM won't boot after restore

Common causes:

1. Secure Boot enabled in VM (disable in VM settings)
2. Wrong boot order (set boot to scsi0)
3. EFI partition not restored (ensure you backed up entire disk, not just a partition)

Fix:

# In Proxmox VM settings:
# Options → Boot Order → Enable scsi0, move to top
# Options → BIOS → SeaBIOS (or OVMF if original was UEFI)

"Not enough space" error during block device backup

Problem: Disk is large, PBS datastore is full

Solutions:

1. Clean old backups: proxmox-backup-client prune
2. Run garbage collection on PBS
3. Add more storage to PBS
4. Switch to file-level only or increase prune frequency

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FAQ

Q: Can I backup just one partition instead of entire disk?
A: Yes! During setup, specify /dev/sda1 instead of /dev/sda. However, you won't be able to directly boot this as a VM without manual partition table recreation.

Q: Will hybrid backup run two backups simultaneously?
A: No. On Sundays, it runs file backup first, then block backup. They're sequential.

Q: Can I change the weekly block backup day from Sunday?
A: Yes! Edit /etc/proxmox-backup-client/backup.sh and change [ "$(date +%u)" -eq 7 ] to different day (1=Monday, 7=Sunday).

Q: Does block device backup require downtime?
A: No, but it's a "hot backup" of a running system, so minor inconsistencies possible. For critical systems, consider backing up while system is idle or from Live USB.

Q: Can I restore a block backup to smaller disk?
A: No, target must be >= original size. You CAN restore file-level backups to any size disk.

Q: Do I need encryption for block device backups?
A: YES! Block device backups contain everything including swap (which may have passwords/keys). Always enable encryption.

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Quick Command Reference

# List all backups
proxmox-backup-client snapshot list

# Restore file-level backup
proxmox-backup-client restore host/laptop/DATE root.pxar /restore/path

# Restore block device to disk
proxmox-backup-client restore host/laptop/DATE sda.img /dev/sdX

# Restore block device to VM disk
proxmox-backup-client restore host/laptop/DATE sda.img /dev/pve/vm-ID-disk-0

# Mount backup for browsing (file-level only)
proxmox-backup-client mount host/laptop/DATE root.pxar /mnt

# Check backup size
proxmox-backup-client snapshot list --output-format json | jq

# Manual block device backup
proxmox-backup-client backup sda.img:/dev/sda