Failed to mount Pool(tank) due to an unknown reason. Command used ['/usr/bin/mount', '/dev/disk/by-label/tank', '/mnt2/tank']

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Brief description of the problem

pools not mounted after restoring Rockstar virtual machine

Detailed step by step instructions to reproduce the problem

have moved Rockstar virtual machine to a new hot - imported and passed through storage disks, system dees disks, but not import pools on them

Web-UI screenshot

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Error Traceback provided on the Web-UI

        Traceback (most recent call last):

File “/opt/rockstor/src/rockstor/rest_framework_custom/”, line 41, in _handle_exception
File “/opt/rockstor/src/rockstor/storageadmin/views/”, line 49, in get_queryset
File “/opt/rockstor/.venv/lib/python2.7/site-packages/django/utils/”, line 185, in inner
return func(*args, **kwargs)
File “/opt/rockstor/src/rockstor/storageadmin/views/”, line 59, in _scrub_status
cur_status = scrub_status(pool, btrfsprogs_legacy())
File “/opt/rockstor/src/rockstor/fs/”, line 1936, in scrub_status
mnt_pt = mount_root(pool)
File “/opt/rockstor/src/rockstor/fs/”, line 795, in mount_root
“Command used {}”.format(, mnt_cmd)
Exception: Failed to mount Pool(tank) due to an unknown reason. Command used [‘/usr/bin/mount’, ‘/dev/disk/by-label/tank’, ‘/mnt2/tank’]

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@rabbifede welcome to the Rockstor community.

While I don’t have an answer for you at this time, could you specify a bit more on what your setup is like the version of Rockstor you’re running. What are you using for virtualization (VMWare, Virtualbox, etc.)?

I assume, you only moved the VM to a new host, but the disks were taken from your old setup/host combination, meaning the tank pool was originally created using the VM before you moved it?


Sorry, Rockstor version 4.6.1-0

I’m on proxmox 8.1. yes, pool created CA an year ago on proxmox, probably lower version (was anyway updated to 8.1 earlier this year)

by they way, disk are shown as detached:

How to re-attach them?

the detached prefix usually indicates, that the system does not see the disk, however the disk attributes are still in the Rockstor database. I am assuming when you hit the rescan button on the disk page, nothing changes?

Since I don’t really know proxmox operations/setup, on the new host do you have to “introduce” the disks again explicitly to the VM, so it can see them? And could it be that, when that’s done, the device UUIDs/IDs change?

If you run this from the command line on your VM:


what does it show?

@phillxnet, any other suggestions on where to look?



hitting "rescan"names of drives change. And still they re detached

Proxmox - at least on hypervisor side - sees the disks, shall I try to re-pass them through by id name and start VM, hopefully then Rockstar VM will imported automatically? I hope this is the idea at least?

Right now VM is turned off

1 Like

probably some names changed moving from one machine to other. Have “deconnected” and re-passed through disks by id, now pool is up and running :slight_smile:

Sorry for wasting your time !


@rabbifede, all good!

This is always good information to know about, since quite a few forum members (myself included for testing) use VMs for either their production setup or testing out Rockstor, so these kinds of details pertaining to the virtualization solution (in this case proxmox) can likely be helpful for others down the line.


I think this change in IDs is related how we represent detached disks. Looking at @phillxnet 's wikified entry for device management:

where a fake UUID is generated in conjunction with the detached status, hence a rescan of these types of devices will result in changed names, but the status will remain the same.