Create a VM with an existing iSCSI disk

nodje

Re: how to create a VM and with an imported VHD disk?

Looking at this thread to understand how to create a new VM without creating a Disk, I followed @Danp advice to create the VM without disk to Attach one later on.

Unfortunately, there doesn't seem to be a way to attach an entire iSCSI SR as a Disk to a VM.

To provide context about what I'm trying to do:
I have an UEFI VM running under TrueNAS where the main storage is a Zvol. Trying to transfer the VM to XCP-NG, I can share this zvol with iSCSI and mount the zvol on XCP-NG with XOA.

But AFAIK, there aren't any option to directly use the iSCSI storage as a VM disk.
(On Proxmox there's this option called "Use LUN directly" which does exactly this)

Here's what is on the zvol:

Disk /dev/zvol/tank/ubuntudockerhost-0vhbns-clone: 80 GiB, 85899345920 bytes, 167772160 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 16384 bytes
I/O size (minimum/optimal): 16384 bytes / 33554432 bytes
Disklabel type: gpt
Disk identifier: F02887A7-E662-44BC-83A5-6905B15FF0EE

Device Start End Sectors Size Type
/dev/zvol/tank/ubuntudockerhost-0vhbns-clone1 2048 1050623 1048576 512M EFI System
/dev/zvol/tank/ubuntudockerhost-0vhbns-clone2 1050624 3147775 2097152 1G Linux filesystem
/dev/zvol/tank/ubuntudockerhost-0vhbns-clone3 3147776 167772126 164624351 78.5G Linux filesystem

And here's what I can see on XCP-NG.
I'm guessing the LVM VG created on the device means that the original partitions on the volume have been overrided.

[14:20 xcp-ng-truenas ~]# lsblk
NAME                                                                                              MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb                                                                                                 8:16   0    80G  0 disk 
└─VG_XenStorage--630141c0--1a17--7252--d2a0--aa31476eccbf-MGT                                     253:1    0     4M  0 lvm

Is there anyway to achieve an iSCSI mount without automatic LVM VG creation?

olivierlambert

Ping @ronan-a or @dthenot I'm not sure it's easy to do that (except using maybe having a first system disk on a regular SR and then mount the iSCSI share after the VM boots as a "regular" share inside the guest OS)

ronan-a

@nodje said in Create a VM with an existing iSCSI disk:

Is there anyway to achieve an iSCSI mount without automatic LVM VG creation?

You can try with the "RawISCSISR" driver but it's not really tested on our side, I can't confirm that it will work. It doesn't support creation of VDIs but you can use it to access existing LUNs on a target.

nodje

@ronan-a Any more information about RawISCSISR usage?
I can't seem to find any good match on the web.