[PVE-User] Matching WUI VM hardware disks to Linux guest disks

Chris Hofstaedtler | Deduktiva chris.hofstaedtler at deduktiva.com
Tue Nov 10 10:53:31 CET 2020


Hi,

* Eneko Lacunza via pve-user <pve-user at lists.proxmox.com> [201110 09:03]:
> I have hit a simple problem. Let be a VM with 3 disks, with .conf extract:
> 
> scsi0: ceph-proxmox:vm-100-disk-1,cache=writeback,size=6G
> scsi1: ceph-proxmox:vm-100-disk-0,cache=writeback,size=400G
> scsi2: ceph-proxmox:vm-100-disk-3,cache=writeback,size=400G
> 
> We have two virtual disks with identical size (400G).
> 
> How can I be sure what device on Linux guest is each?

You can also check - and use in /etc/fstab - the /dev/disk/by-*
symlinks.

In a VM, maybe the most relevant "id" is the actual path.
/dev/disk/by-path has these links (in my case):

  pci-0000:06:05.0-scsi-0:0:0:0 -> sda
  pci-0000:00:05.0-scsi-0:0:0:1 -> sdb

If your sdb/sdc are swapped, the SCSI IDs in the path should still
be correct.

If you don't like the pci path in there, /dev/disk/by-id has:
  scsi-0QEMU_QEMU_HARDDISK_drive-scsi0 -> sda
  scsi-0QEMU_QEMU_HARDDISK_drive-scsi1 -> sdb

But you'll have to check if those match with the VM settings (I'd
expect them to).

As you've discovered and others have said, lsscsi, or lsblk -S can
be used to see the SCSI IDs, too. The same info is also availabe
from udevadm: udevadm info /dev/sda
If you dig around in /sys, it's also there ;-)

HTH,
Chris
-- 
Chris Hofstaedtler / Deduktiva GmbH (FN 418592 b, HG Wien)
www.deduktiva.com / +43 1 353 1707



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