qubes-doc/user/troubleshooting/disk-troubleshooting.rst

====================
Disk troubleshooting
====================


"Out of disk space" error
-------------------------


If the disk is completely full, you will get an ``Out of disk space``
error that may crash your system because Dom0 does not have enough disk
space to work. So it’s good practice to regularly check disk space
usage. Running the ``df -h`` command in dom0 terminal will show some
information, but not include all the relevant details. The Qubes user
interface provides a disk space widget. If you are unable to access the
interface, the command line version is running ``sudo lvs | head`` and
looking at top entry for LVM pool. For example:

.. code:: bash

      LV                                            VG         Attr       LSize   Pool   Origin                                        Data%  Meta%  Move Log Cpy%Sync Convert
       pool00                                        qubes_dom0 twi-aotz-- 453.17g                                                      89.95  69.78
       root                                          qubes_dom0 Vwi-aotz-- 453.17g pool00                                               5.87
       swap                                          qubes_dom0 -wi-ao----   7.57g



If you run ``df -h``, it only shows the information in the ``root`` line
(which is already included in the ``pool00`` line). As you can see, the
``sudo lvs | head`` command includes additional important columns
``Data%`` and ``Meta%``, shown in the above example to have the values
89% and 69% respectively.

If your system is able to boot, but cannot load a desktop environment,
it is possible to login to dom0 terminal with Alt + Ctrl + F2.

If this does not work, check the size of /var/lib/qubes/qubes.xml. If it
is zero, you’ll need to use one of the file backup (stored in
/var/lib/qubes/backup), hopefully you have the current data there. Find
the most recent one and place in /var/lib/qubes/qubes.xml instead of the
empty file.

In any case you’ll need some disk space to start the VM. Check ``df -h``
output if you have some. If not, here are some hints how to free some
disk space:

1. Clean yum cache.

   .. code:: bash

         sudo dnf clean all



2. Delete ``.img`` files of a less important VM, which can be found in
   ``/var/lib/qubes/appvms/``. Then, when the system is working again,
   clean up the rest.

   .. code:: bash

         qvm-remove <VMname>


   With this method, you lose the data of one VM, but it’ll work more
   reliably.

3. Decrease the filesystem safety margin (5% by default).

   .. code:: bash

         sudo tune2fs -m 4 /dev/mapper/vg_dom0-lv_root



4. Remove some unneeded files in dom0 home (if you have any, most likely
   not). Also look for unneeded files in ``/var/log`` in dom0, and
   ``/var/log/qubes``.



The above steps applies to old VM disks format. These steps may work on
Qubes 4.0, but are not default anymore. By default, Qubes 4.0 now uses
LVM. The equivalent steps are:

1. Get a list of VM disks using ``sudo lvs``.

2. Use ``sudo lvremove qubes_dom0/<name>`` to remove backup copies of
   some less important VMs – entries with ``-back`` in their name.

3. If that isn’t enough, remove actual disks of less important VMs.
   NOTE: You will lose the data of that VM, but your system will resume
   working.



For example:

.. code:: bash

      $ sudo lvs
        LV                                            VG         Attr       LSize   Pool   Origin                                        Data%  Meta%  Move Log Cpy%Sync Convert
        pool00                                        qubes_dom0 twi-aotz-- 453.17g                                                      89.95  69.78
        root                                          qubes_dom0 Vwi-aotz-- 453.17g pool00                                               5.87
        swap                                          qubes_dom0 -wi-ao----   7.57g
      (...)
        vm-d10test-private                            qubes_dom0 Vwi-a-tz--   2.00g pool00 vm-d10test-private-1600961860-back            29.27
        vm-d10test-private-1600961860-back            qubes_dom0 Vwi-a-tz--   2.00g pool00                                               4.87
        vm-d10test-standalone-private                 qubes_dom0 Vwi-a-tz--   2.00g pool00 vm-d10test-standalone-private-1580772439-back 4.90
        vm-d10test-standalone-private-1580772439-back qubes_dom0 Vwi-a-tz--   2.00g pool00                                               4.87
        vm-d10test-standalone-root                    qubes_dom0 Vwi-a-tz--  10.00g pool00 vm-d10test-standalone-root-1580772439-back    43.37
        vm-d10test-standalone-root-1580772439-back    qubes_dom0 Vwi-a-tz--  10.00g pool00                                               42.05
        vm-debian-10-my-private                       qubes_dom0 Vwi-a-tz--   2.00g pool00                                               4.96
        vm-debian-10-my-root                          qubes_dom0 Vwi-a-tz--  10.00g pool00 vm-debian-10-my-root-1565013689-back          57.99
        vm-debian-10-my-root-1565013689-back          qubes_dom0 Vwi-a-tz--  10.00g pool00                                               56.55
        vm-debian-10-private                          qubes_dom0 Vwi-a-tz--   2.00g pool00                                               4.94
        vm-debian-10-root                             qubes_dom0 Vwi-a-tz--  10.00g pool00 vm-debian-10-root-1601126126-back             93.44
        vm-debian-10-root-1601126126-back             qubes_dom0 Vwi-a-tz--  10.00g pool00                                               88.75
      (...)
      $ sudo lvremove qubes_dom0/vm-d10test-standalone-root-1580772439-back
      Do you really want to remove and DISCARD active logical volume qubes_dom0/vm-d10test-standalone-root-1580772439-back? [y/n]: y
        Logical volume "vm-d10test-standalone-root-1580772439-back" successfully removed



After freeing some initial space, it may be possible to recover more
space by deleting files in a userVM after connecting to the userVM
terminal:

.. code:: bash

      qvm-start <VMname>
      qvm-console-dispvm <VMname>



Since ``qvm-console-dispvm`` requires working graphical user interface
login, you must first free enough space to be able to start a VM and
login to graphical UI.

Can't resize VM storage / "resize2fs: Permission denied" error
--------------------------------------------------------------


:doc:`Resizing a volume </user/advanced-topics/resize-disk-image>` in the Qubes interface
should be a straightforward process. But sometimes, an attempt to resize
will look like it worked, when it in fact fails silently. If you then
try the same operation in the dom0 console using the
``qvm-volume extend`` command, it fails with the error message:
``resize2fs: Permission denied to resize filesystem``. This error
indicates that a ``resize2fs`` will not work, unless ``fsck`` is run
first. Qubes OS utilities cannot yet handle this case.

To fix this issue:

1. In the dom0 terminal get a root console on the vm (eg. sys-usb) with:

   .. code:: bash

         qvm-console-dispvm sys-usb



2. Unmount everything mounted on the private volume
   ``/dev/xvdb partition``. There are typically several mounts listed in
   ``/etc/mtab``.

3. When you attempt to unmount the ``/home`` directory using the
   ``umount /home`` command, you will encounter an error because there
   are processes using the ``/home`` directory. You can view a list of
   these processes with the ``fuser`` command:

   .. code:: bash

         fuser -m /home





Kill these process until they are all gone using ``kill <process ID>``.

4. Finally, run:

   .. code:: bash

         umount /home
         fsck /dev/xvdb
         resize2fs /dev/xvdb







After restarting your VM, everything should now work as expected. The
private volume size shown externally in the VM’s settings interface is
the same as that seen within the VM.