Resizing the LUN

I use TrueNAS as my iSCSI host. I have the lvm as a Zvol
TrueNAS -> Storage -> Pools
Select the Volume you have attached to proxmox

Increase the value for “Size for this zvol”. Only Increasing is allowed through the webui.

Proxmox resizing

For me the iSCSI drive updated automatically. But if needed you can use iscsiadm --mode session --rescan

Next the lvm physical volume needs resized, That can be done with pvresize /dev/<iscsi-drive>

Now you should be able to see the drive has resized.