Clustered iSCSI as LVM on LVM-Thin SAN

[themmmaroko]

Hello all.

I am aware the issue of configuring LVM-Thin in a clustered environment with shared storage has been extensively discussed and why it is a really bad idea.

However, l would like to ask this question from a different angle. When looking into our SAN storage configuration, there is an option to utilize Thin provisioning at the SAN level (attached image). This led me to thinking whether configuring such provisioned volume as (regular Thick) LVM storage on Proxmox level is viable.
Multipath iSCSI in place; mpath pv dev / vg on PVE.

So with a configuration where VM is assigned a 100 GB disk from LVM PVE storage of which 20 GB is used, hosted on LVM-Thin SAN LUN, only those 20 GB are indeed actually consumed from the SAN.

Does this approach work or is it still in violation of 'single-writer' principle?

Thank you.

 

[bbgeek17]

Does this approach work or is it still in violation of 'single-writer' principle?

Using thin pool inside your storage device is completely independent of client connectivity. You will be completely fine using that option.

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[d.oishi]

My understanding is that even if the SAN is thin-provisioned, Proxmox shared LVM still sees each LUN as fixed-capacity storage. So for a single LUN, the amount of VM disk space you can allocate does not increase beyond the LUN size.

The benefit of SAN thin provisioning is mainly on the backend: it can reduce physical storage consumption and allow you to provision additional LUNs more efficiently. But that also means you need proper capacity monitoring on the SAN side, which makes operations more complicated.

 

[bbgeek17]

@d.oishi , You are correct: regardless of the layer at which thin provisioning is implemented, careful monitoring must be in place. Unexpectedly running out of space is rarely handled gracefully by operating systems or applications.

Cheers,

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox