If you’re planning a deployment on Proxmox VE 9, one of the most critical (and often misunderstood) decisions is: Should you use LVM-thin or LVM (thick) for your VM storage?

This choice directly affects:

• Performance
• Snapshot capability
• Storage efficiency
• High Availability (HA) design

In this guide, we break it down in practical, real-world terms—especially for enterprise environments, SAN-based clusters, and VMware-to-Proxmox migrations.

Understanding the Basics

At its core:

• LVM (Thick) → Fully allocated storage (predictable, stable)
• LVM-Thin → Thin-provisioned storage (flexible, efficient)

But the real difference lies in how storage is allocated and managed internally.

LVM (Thick) — The Enterprise Default

How it works

When you create a VM disk (say 100 GB):

• The full 100 GB is allocated immediately
• Storage is reserved at the block level
• No abstraction or dynamic allocation layer

Why enterprises prefer it

• Predictable performance
• No overcommit risk
• Stable under heavy workloads
• Fully supported for shared storage (iSCSI / FC SAN)

Limitations

• No thin provisioning (wastes unused space)
• No native snapshots (in shared SAN setups)
• Slower provisioning compared to thin

LVM-Thin — Flexible & Feature-Rich

How it works

When you create a 100 GB disk:

• Initially uses almost 0 space
• Grows dynamically as data is written
• Managed via a thin pool with metadata tracking

Why it’s powerful

• Highly space-efficient
• Supports snapshots and clones
• Fast provisioning
• Ideal for dev/test and rapid deployments

Risks

• Thin pool can fill up
• Requires monitoring and alerts
• Slight performance overhead under heavy I/O

What’s New in Proxmox VE 9?

Proxmox 9 introduced: “Snapshots as Volume-Chain” (Technology Preview)

This allows snapshots on LVM (thick) using a new mechanism.

But here’s the reality

• Still experimental
• Not supported on shared storage (iSCSI / FC SAN)
• Performance impact under load

For most enterprise deployments:

This does NOT replace LVM-thin snapshots yet

 

The Critical Difference: Cluster & SAN Support

Shared Storage (iSCSI / FC SAN)

Why?

• LVM-thin is not cluster-safe
• Shared SAN environments require simple, consistent block mapping

Local Storage

Performance Comparison

LVM (Thick)

• Direct block access
• No metadata lookup
• Consistent latency

Best for:

• Databases
• ERP systems
• High IOPS workloads

LVM-Thin

• Metadata layer involved
• Uses CoW for snapshots

Best for:

• Dev/test environments
• Snapshot-heavy workloads
• Rapid provisioning

Snapshot Reality Check

Real-World Deployment Strategy

For Enterprise / Customer Projects

Recommended architecture:

• Shared storage (TrueNAS / FC SAN / iSCSI)
  → LVM (thick)
• Backup strategy
  → Proxmox Backup Server (PBS)
• Snapshots
  → Avoid relying on them

Hybrid Model (Best Practice)

Many advanced deployments use:

• LVM (thick) → production workloads
• LVM-thin → dev/test, staging, snapshots

This gives:

• Stability + flexibility

VMware to Proxmox Migration Tip

If you’re migrating from VMware:

• VMware = thin by default
• Proxmox SAN design = thick by design

Key shift:

Move from “snapshot-heavy workflows” → “backup-first architecture”

 

Final Comparison Table

Final Thoughts

Choosing between LVM-thin and LVM (thick) isn’t just about features—it’s about architecture fit.

If you’re building:

• HA cluster on SAN → go with LVM (thick)
• Flexible local workloads → use LVM-thin

Need Help Designing Your Proxmox Storage?

At Saturn ME, we specialize in:

• Proxmox cluster design (HA, Ceph, SAN)
• VMware to Proxmox migrations
• TrueNAS, Ceph, and hybrid storage architectures
• Performance optimization & troubleshooting

Contact us for a free architecture consultation