When working with templates in Proxmox VE, one of the most important choices you’ll make during VM deployment is whether to create a Full Clone or a Linked Clone.

At first glance, the options look like a simple speed vs size trade-off. In reality, the decision affects:

• storage usage
• provisioning speed
• VM independence
• migration flexibility
• risk exposure
• long-term maintainability

Choosing the wrong clone type can lead to wasted storage — or worse — broken VMs later when a template is removed.

This guide explains the differences clearly and gives practical rules for production vs lab environments.

What Happens When You Clone in Proxmox?

When you clone a VM (usually from a template), Proxmox creates a new VM disk based on the source image.

There are two ways this can happen:

• Full Clone → complete disk copy
• Linked Clone → shared base + delta changes

Think of it like this:

• Full clone = photocopy of the entire book
• Linked clone = reference the original book plus your handwritten notes

Linked Clone — Fast and Space Efficient

A linked clone shares the template’s base disk and stores only the changes made by the new VM.

The template disk becomes read-only, and each linked clone writes only its differences.

How It Works

Template disk (read-only base)
        ↑
   shared by
        ↑
Linked clone → stores only changed blocks

Advantages of Linked Clones

Extremely fast to create

Linked clones are created in seconds because Proxmox does not need to copy the full disk.

Very low storage usage

Only modified data consumes space — often just a small fraction of the template size.

Ideal for scale-out scenarios

Useful when you need many similar VMs quickly.

Common use cases:

• lab environments
• CI/CD runners
• training classrooms
• test clusters
• development sandboxes
• short-lived workloads
• Kubernetes worker pools

Disadvantages of Linked Clones

Dependency on template disk

If the template disk is deleted, corrupted, or lost, linked clones can break.

Not ideal for long-lived critical VMs

They are best for disposable or reproducible workloads.

Snapshot chains grow

Heavy snapshot use can create deeper dependency chains and slower performance over time.

Less flexible storage migration

Moving linked clones between storage backends is more complex.

Storage Backends That Support Linked Clones

Linked clones require snapshot-capable storage, such as:

• ZFS
• Ceph RBD
• LVM-thin
• QCOW2-based storage

They are not supported on plain LVM or simple directory storage without snapshot capability.

Full Clone — Independent and Production-Safe

A full clone creates a complete, independent copy of the source VM disk.

There are no dependencies on the template after cloning.

How It Works

Template disk → full copy → new VM disk

Each VM stands alone.

Advantages of Full Clones

Fully independent

The cloned VM has its own disk and does not rely on the template anymore.

Safer for production

The template can be deleted later without affecting the VM.

Easy to migrate storage

Full clones move cleanly between storage systems and nodes.

Clean snapshot structure

No deep dependency chains.

Better for long-term workloads

Suitable for servers that will run for months or years.

Disadvantages of Full Clones

Slower to create

The disk must be fully copied.

Uses full disk space

Consumes roughly the same size as the original disk.

Higher IO during creation

Clone operations can generate noticeable storage load.

Side-by-Side Comparison

When You Should Use Linked Clones

Choose linked clones when:

• VMs are temporary
• you need many instances quickly
• storage efficiency matters
• environment is reproducible
• template will be preserved
• workloads are disposable

Typical scenarios:

• development labs
• automated test farms
• classroom environments
• CI runners
• short-lived container hosts

When You Should Use Full Clones

Choose full clones when:

• VMs are production workloads
• uptime matters
• template lifecycle is uncertain
• storage migration is expected
• VM will live long-term
• data is important

Typical scenarios:

• databases
• monitoring servers
• Ceph nodes
• infrastructure services
• application servers
• long-running workloads

How to Choose in Proxmox GUI

When cloning from a template:

Right click Template → Clone

You will see a checkbox:

Linked Clone

• Checked → Linked clone
• Unchecked → Full clone

How to Clone from CLI

Linked clone

qm clone 9000 101 --name vm101 --linked 1

Full clone

qm clone 9000 102 --name vm102

Common Real-World Mistake

A frequent mistake is using linked clones for production and later deleting or moving the template.

Result: broken VMs.

If a VM is important or long-lived, use a full clone.

Simple Decision Rule

Use this rule of thumb:

Many and temporary = Linked clone
Important and long-term = Full clone

Final Takeaway

Linked clones optimize for speed and storage efficiency. Full clones optimize for independence and safety.

Both are powerful when used in the right context.

Design your cloning strategy around workload lifespan and risk tolerance, not just how fast the clone finishes.