iSCSI with 2 LUNs, configured differently

[paulatz]

Hello, I have a proxmox cluster connected to an iSCSI disk, and I would like to configure it in a way that I'm not sure is possible. The HP iSCSI box export different volumes as different LUNs if I'm connecting them to the same targets, I have not managed to export them as different iSCSI targets.

Initially, I had a single target, I connected it with no issues and used it directly as a virtual disk in a VM that acts as a samba server. When attaching the iSCSI to proxmox I did *not* check "use LUNs directly", but this did not seem to cause any problem.

Later, I created and exported a second volume on the HP box, and trying to find how to expose it in proxmox, I finally stumbled upon the "use LUNs directly" option, checked it, and this now allows me to use each LUNs as a different disk in any VM of choice.

However, what I would like to do, is use this second LUN as a backup storage for proxmox. If I go to "storage" and choose "Add -> ZFS over iSCSI" there is no option to choose only one of the LUNs, I'm a bit afraid that it may wipe the VM disk. I have a backup, but that would be annoying to restore (100TB).

Any hint on how to do this operation safely? I can do it by command line and config files if necessary.

thank you!

 

[bbgeek17]

ZFS over iSCSI is likely an incompatible technology with your type of storage.
If you want to use a LUN directly on your hypervisor, you have two primary options:
a) attach the lun manually, partition and mount it
b) use PVE to add iSCSI storage (already done?), place LVM and then a filesystem on it

---

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

 

[paulatz]

Thank you, I saw later that indeed "zfs over iscsi" does not do what I thought it did. Yes, I could manually put a filesystem on the ZFS LUN and mount it manually, but that would be sort of clumsy because as it is exposed on all the nodes, and if I mount on more than one, chaos would ensue. I think I'll add a backup server instead to take care of the sharing.

 

[bbgeek17]

Yes, if you thought about using that lun as shared storage, then you need a different approach.

Using it for PBS is one way, you can find a sample discussion here: https://forum.proxmox.com/threads/playground-time-virtual-pbs-with-iscsi-backend.88395/

However, keep in mind that you will likely not be able to manage the iSCSI disk with PBS end to end, as it explicitly skips iSCSI disks:
proxmox-backup/src/tools/disks/mod.rs

if let Ok(target) = std::fs::read_link(&sys_path) {
            if let Some(target) = target.to_str() {
                if ISCSI_PATH_REGEX.is_match(target) {
                    continue;
                } // skip iSCSI devices
            }
        }

Which results in "proxmox-backup-manager disk list" not showing the disks.

---

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