Virt-resize

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https://linux.die.net/man/1/virt-resize

Example

Reference: http://wiki.docking.org/index.php/To_resize_a_virtual_drive

Overview: qemu-img resize -> virt-resize -> (Check virt-filesystems) -> lvextend --resizefs

1) Backup 

cp my_machine.qcow2 my_machine-ORIGIN.qcow2 (progress -m to track status)

2) Resize:

virt-resize --expand /dev/sda4 my_machine-ORIGIN.qcow2 my_machine.qcow2z

3) To verify name of your devices you can use:

virt-filesystems --partitions --long -a VM_NAME.qcow2

virt-resize --expand /dev/sda4 my_machine-ORIGIN.qcow2 my_machine.qcow2
[   0.0] Examining my_machine.qcow
**********

Summary of changes:

/dev/sda1: This partition will be left alone.

/dev/sda2: This partition will be left alone.

/dev/sda3: This partition will be left alone.

/dev/sda4: This partition will be resized from 99.3G to 299.3G.  The LVM PV
on /dev/sda4 will be expanded using the 'pvresize' method.

**********
[   5.2] Setting up initial partition table on my_machine.qcow2
[  17.5] Copying /dev/sda1
[  17.5] Copying /dev/sda2
[  18.0] Copying /dev/sda3
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00
[ 258.7] Expanding /dev/sda4 using the 'pvresize' method

Resize operation completed with no errors.  Before deleting the old disk,
carefully check that the resized disk boots and works correctly.

Use: virt-filesystems to check image after executing virt-resize

Start your machine: virsh start VM_NAME and discard your backups is everything is working properly.

Virt-resize execution with errors

Failed to get "write" lock

virt-resize: error: libguestfs error: guestfs_launch failed.
This usually means the libguestfs appliance failed to start or crashed.
Do:
  export LIBGUESTFS_DEBUG=1 LIBGUESTFS_TRACE=1
and run the command again.  For further information, read:
  http://libguestfs.org/guestfs-faq.1.html#debugging-libguestfs
You can also run 'libguestfs-test-tool' and post the *complete* output
into a bug report or message to the libguestfs mailing list.

If reporting bugs, run virt-resize with debugging enabled and include the
complete output:

  virt-resize -v -x [...]


After debugging: 
 qemu-system-x86_64: -drive file=/path/to/image/VM_NAME.qcow2,cache=unsafe,id=hd1,if=none: 
 Failed to get "write" lock
 Is another process using the image?

partition not found in the source disk image

libguestfs: trace: lvs = []
libguestfs: trace: canonical_device_name "/dev/vdb1"
libguestfs: trace: canonical_device_name = "/dev/sdb1"
virt-resize: error: /dev/sdb1: partition not found in the source disk image
(this error came from '--expand' option on the command line).  Try running
this command: virt-filesystems --partitions --long -a
VM_NAME.qcow2

Related commands

• qemu-img resize
• lvextend --resizefs
• virt-filesystems

Activities

• Extend LVM on qcow2 images

See also

• KVM, Installation, QEMU, virsh, virtinst, libguestfs-tools, libvirt, qemu, Red Hat Virtualization (RHV), MacVTap, Virtio, oVirt, KVM services, KVM networking, KVM graphics, CPU, KVM on ARM
• libguestfs-tools: virt-sysprep, virt-clone, virt-builder, virt-customize, virt-resize, virt-rescue, virt-sparsify, guestmount, guestfish, virt-inspector, virt-cat, virt-log, virt-df, virt-ls, virt-filesystems, virt-list-filesystems, virt-edit