Thin provisioning not reflected in Proxmox LVM shared storage over FC multipath

[danht1710]

Hi team,

I’m running a 4-node Proxmox cluster (version 9.1.6) connected to a Pure Storage SAN over FC (32Gb, dual port) using multipath.

On the SAN side, volumes are configured with thin provisioning and data reduction. I present LUNs to all nodes and configure them as shared LVM storage in Proxmox (not using LVM-thin because I need shared storage across the cluster).

The issue I’m facing is related to storage reporting.

For example, I create 2 VMs, each with a 50GB disk, but the actual data written inside the VMs is only around 10GB in total.

• On the SAN, usage is correctly reported as ~10GB.
• On Proxmox, the storage shows 100GB allocated.

This creates operational challenges because Proxmox considers the storage nearly full much earlier than the SAN actually is. As a result, I have to provision additional LUNs and configure more multipath devices, which increases complexity.

I understand that LVM is block-based and reports allocated capacity, but I would like to ask if there is any way for Proxmox to reflect actual used capacity (thin-aware) when using shared FC storage.

Due to performance and architecture requirements, I cannot switch to Ceph, ZFS, NFS, or LVM-thin. I need to keep FC block storage with multipath for consistent performance.

Could you please advise:

• Is there any supported way for Proxmox to display real usage (similar to SAN) instead of allocated size when using shared LVM?
• Is there any integration, plugin, or recommended approach to obtain thin provisioning awareness from the backend storage?
• Or is this a known limitation of LVM-based shared storage in Proxmox?

Thanks.

 

[namthp]

I’m running into the same issue as you. Has anyone here managed to resolve it yet?

 

[LnxBil]

I understand that LVM is block-based and reports allocated capacity, but I would like to ask if there is any way for Proxmox to reflect actual used capacity (thin-aware) when using shared FC storage.

No, you have to have proper integration from the SAN vendor in order to do this. Thick LVM justs sees the storage as used, as you described.

Is there any supported way for Proxmox to display real usage (similar to SAN) instead of allocated size when using shared LVM?

No, storage is assumed to be thick and reporting correct values is a SAN problem.

Is there any integration, plugin, or recommended approach to obtain thin provisioning awareness from the backend storage?

Ask your SAN vendor what he has. There are some floating around for some vendors.

Or is this a known limitation of LVM-based shared storage in Proxmox?

Yes, LVM thick is thick, so allocated is allocated.


There are SAN vendors tha provide proper integration into PVE, but you need to buy a new SAN.