No LVM2 tool in TrueNAS Scale

TrueNAS General
1

I’m testing restoring rsync backup from TrueNAS Scale. But one obstacle is that TrueNAS scale doesn’t install LVM2 tool. I can’t mount lvs/vgs in the target restore drive. I can’t do apt-get.

How to hack it?

The AI RAG from TrueNAS Documentation Hub suggests me to do it from a VM and passthrough my USB hard drive hooking to the NAS. But this sounds silly.

The ChatGPT suggest me to do it inside a ubuntu container:

# Run Ubuntu container with LVM access
docker run -it --privileged \
  -v /dev:/dev \
  -v /mnt:/host-mnt \
  ubuntu:22.04 bash

# Inside container:
apt update && apt install lvm2

I entered into the ubuntu container. But it immediately got bitten by the fact TrueNAS kernel doesn’t have device-mapper driver. I bet this won’t fly in VM case, either.

root@0fcc857f2579:/host-mnt/tank/linux-backup/t30# lvs
  /dev/mapper/control: open failed: No such device
  Failure to communicate with kernel device-mapper driver.
  Check that device-mapper is available in the kernel.
  Incompatible libdevmapper 1.02.175 (2021-01-08) and kernel driver (unknown version).
  LV      VG        Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv_home vg_2tb_hd -wi-XX---- <215.03g
  lv_root vg_2tb_hd -wi-XX----  200.00g
  lv_swap vg_2tb_hd -wi-XX----   64.00g
  lv_var  vg_2tb_hd -wi-XX----  400.00g

Why TrueNAS Scale doesn’t support LVM and device/mapper in the kernel OTB? Not everyone can afford 10GB Ethernet setup. When I do restore, I prefer to hook up a USB3 hard drive. It is faster than 1GB Ethernet or 2.5GB Ethernet.

2

Because it’s ZFS-only, and has been for at least the last ten years.

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