iSCSI with 2 LUNs, configured differently

paulatz

New Member
Jul 27, 2023
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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!
 
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
 
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.
 
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
Code:
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
 

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