Unlock new capabilities for your self-hosting setup with Proxmox VE 9! This latest release introduces a groundbreaking “snapshots as volume chains” feature, transforming how you manage virtual machine snapshots on iSCSI LUNs. No longer tied to restrictive storage-level features, this innovation brings VMware-like snapshot flexibility to Proxmox, a significant boon for homelab enthusiasts and anyone seeking robust virtualisation solutions. Discover how this technology preview simplifies your workflow, enhances data redundancy, and prepares you for the future of your infrastructure.
Unlocking Advanced Snapshots: Proxmox VE 9’s Volume Chains for iSCSI Storage
One of the most anticipated features in Proxmox VE 9 Server is its enhanced snapshot capability, especially for thick-provisioned LUNs with iSCSI and NFS. For many who’ve transitioned from VMware, the previous absence of robust snapshot support for traditional SAN technologies was a significant hurdle, often nudging users towards Ceph storage. Now, Proxmox introduces “snapshots as volume chains,” a game-changer that addresses this long-standing limitation. Let’s explore why this is a monumental leap for virtualisation management and how to configure it.
What are Snapshots as Volume Chains?
In earlier Proxmox versions, snapshot implementation varied significantly based on the storage backend. ZFS, LVM-Thin, and Ceph RBD offered native snapshot support, while file-based storage like NFS/CIFS relied on QCOW2 overlays. iSCSI LUNs, however, often lacked integrated snapshot capabilities, forcing reliance on complex, often unavailable, storage-level features.
With the “Snapshots as Volume Chains” feature in Proxmox VE 9, Proxmox shifts its approach for specific backend storage technologies. Instead of a one-disk-per-VM approach for snapshots, it now creates a chain of volumes (base + delta files). This mirrors the familiar concept in VMware vSphere, where each snapshot represents a new delta volume linked to its parent, similar to how QCOW2 works with backing files.
For iSCSI, this means Proxmox can now manage snapshots internally without full dependency on the SAN’s native snapshot features. This empowers you with snapshots even on simpler or generic iSCSI targets, expanding the versatility for self-hosting and homelab environments.
Why This Matters for iSCSI Storage
Historically, iSCSI users in Proxmox faced a tough choice: forego snapshots or invest in enterprise SAN arrays with native LUN snapshot features. This wasn’t ideal for budget-friendly homelab setups, where users commonly leverage FreeNAS/TrueNAS, Synology, or other commodity NAS devices as iSCSI targets.
Now, Proxmox 9’s volume-chain approach brings significant advantages:
- Storage Agnostic Snapshots: As long as your iSCSI target supports standard LUNs, Proxmox can manage its own snapshot chains, offering unparalleled flexibility.
- Simplified Clone Operations: Create linked clones directly from snapshot points without needing full-volume duplication, saving valuable storage space and time.
- More Efficient Incremental Backups: Future backup solutions, including potentially Proxmox Backup Server, can leverage these snapshots to reference only changed blocks, leading to faster and more efficient data redundancy operations.
- Faster Testing and Rollbacks: Quickly create a snapshot before testing new configurations or updates, then revert in seconds if issues arise.
For former VMware administrators or those managing production environments, the maturing storage features in Proxmox could significantly accelerate migrations, especially given recent market changes from other hypervisor vendors.
“Technology Preview”: What You Need to Know
It’s crucial to understand that “Snapshots as Volume Chains” for iSCSI is currently a “Technology Preview” feature. This means it’s not yet officially supported for production environments. There’s a possibility of performance quirks or unexpected behavior. Backup and restore functionalities might not fully support them yet, and the feature is still under active development, subject to change in future releases.
That said, Proxmox is known for rapidly developing and stabilizing such features. Testing it now provides a valuable head start, preparing you for its general availability (GA), potentially in Proxmox 9.1 or later.
Setting Up iSCSI Storage in Proxmox 9
Let’s quickly review the process of enabling an iSCSI target in Proxmox VE 9. The steps remain consistent, whether you’re using FreeNAS, TrueNAS, Synology, or another iSCSI target for your virtualisation needs.
Step 1: Add the iSCSI Target
- In the Proxmox web UI, navigate to Datacenter > Storage.
- Click Add > iSCSI.
- Enter your desired Storage ID (e.g.,
iscsi-test), the Portal (IP address or hostname of your iSCSI target), and the Target (the IQN of your iSCSI LUN). - Click Add.
Step 2: Add an LVM Group on iSCSI
If your iSCSI LUN will host VM disks, you’ll typically add an LVM Group on top of it:
- Go to Datacenter > Storage > Add > LVM.
- Select your newly added iSCSI device from the dropdown.
- Assign a meaningful Volume Group name (e.g.,
lvm-iscsi-test).
Important: Do not click “Add” yet! Proceed to the next step.
Enabling Snapshots as Volume Chains on Your iSCSI LVM
The key to unlocking the new snapshot capability lies in a specific checkbox within the LVM storage configuration dialog.
Step 3: Enable the Tech Preview Setting
- While still in the LVM storage configuration dialog, click the Advanced checkbox.
- Locate and check the “Enable Snapshots as Volume Chains (Technology Preview)” option.
- Now, click Add to save your changes.
Once enabled, any VM disk stored on this LVM-backed iSCSI storage will automatically utilize the new volume-chain snapshot method.
Creating and Testing Snapshots on iSCSI LVM
With the feature enabled, you can now create snapshots just like you would on ZFS or QCOW2-backed storage.
Step 4: Create a Snapshot
- Select a VM whose disk resides on your iSCSI-backed LVM.
- Navigate to the Snapshots tab and click Take Snapshot.
- Provide a descriptive Name (e.g.,
pre-upgrade-test) and decide whether to include VM memory. - Click Take Snapshot.
Upon completion, the new snapshot will appear in your VM’s Snapshots menu, confirming its successful creation.
Step 5: Verify the Volume Chain
While the Proxmox UI displays these as standard snapshots, the underlying structure is a volume-linked chain. To verify:
- Access the Proxmox shell.
- Use commands like
lvdisplayto inspect the volume chain structure. You should observe the base logical volume alongside any new, linked delta volumes representing your snapshots.
Step 6: Test Rollback
- Make a noticeable change within your VM (e.g., install updates, modify a configuration file).
- Go back to the VM’s Snapshots tab and select the snapshot you wish to revert to.
- Click Rollback and confirm. Verify that the VM’s disk state successfully reverts to the point of the snapshot.
Use Cases for the New Snapshots
The applications for this enhanced snapshot functionality are extensive, leveraging familiar benefits that have been staples of virtualisation for decades:
- Test Environments: Rapidly test different scenarios, apply patches, or experiment with configurations in your homelab, knowing you can instantly revert.
- Pre-Upgrade Safety: A crucial step before applying OS or application updates; take a snapshot to create an immediate rollback point if anything breaks.
- Linked Clones: These snapshots form the foundation for creating disk-efficient linked clones, allowing faster VM provisioning from a single golden image.
- Backup Technologies: This new capability is poised to be leveraged by backup vendors and Proxmox Backup Server (PBS), potentially leading to more efficient and quicker backup operations for improved data redundancy.
Downsides and Limitations
While a significant advancement, it’s important to acknowledge general snapshot tradeoffs and specific limitations of the current “snapshots as volume chains” implementation in Proxmox VE 9:
- Performance Impact: Long snapshot chains can introduce I/O overhead as Proxmox needs to traverse more layers for read operations.
- Merge Operations: Deleting a snapshot in the middle of a chain requires merging changes into either the parent or child volume, which can be time-consuming, especially for large volumes with significant changes.
- Backup Strategy: Always conduct thorough tests with your Proxmox Backup Server or other backup solutions to ensure they fully support and can correctly restore VMs with chained snapshots.
A notable current limitation of the “snapshots as volume chains” feature is that it only allows rolling back to the most recent snapshot in the chain. If you have multiple snapshots (e.g., Snapshot 1, Snapshot 2, Snapshot 3), you can only revert to Snapshot 3. Attempting to roll back to an earlier snapshot (like Snapshot 1) when a newer one exists will result in an error.
Hopefully, Proxmox will address this limitation in a future release, providing greater flexibility for point-in-time recovery.
Wrapping it Up
Despite the current limitation on rollback flexibility, the introduction of “snapshots as volume chains” for virtual machines on iSCSI LUNs in Proxmox VE 9 marks a monumental step forward. This feature finally grants Proxmox users snapshot capabilities on traditional storage technologies, enabling a vendor-agnostic approach without relying on specific hardware. While still in Technology Preview, making it unsuitable for immediate production deployment, it’s an indispensable feature for anyone running an iSCSI-backed homelab or planning future virtualisation migrations. Start testing this today to gain firsthand experience with what promises to be a core feature for future self-hosting and enterprise deployments. Your feedback to the Proxmox community on this feature’s impact will be invaluable!
- Pro Tip: What is a key limitation to be aware of when using these new snapshots?
- A significant current limitation is that you can only roll back to the most recent snapshot in a volume chain. If you have multiple snapshots (e.g., Snap A, Snap B, Snap C, where C is the newest), you can only revert to Snap C. You cannot directly roll back to an earlier snapshot (like Snap A or Snap B) if a newer one exists in the chain.