How to extend a Ravada Linux guest’s disk space

Extending a Linux disk drive in a virtual machine is a straightforward process. Follow this guide carefully.

The process requires a change in the Ravada frontend and then use the command line in the host to resize the partition.

Shutdown

The virtual machine must be down to resize the volumes. Press Shutdown button in the Admin Tools.

Backup

Make a backup of the disk volumes. The easiest way is to compact the virtual machine. After that you should have a copy of all the volumes in the images directory. Usually located at /var/lib/libvirt/images.

Expand the volume

Go to the Hardware tab in the virtual machine settings. Select the disk drive you want to extend and type the desired size of the volume.

Remove and create the partition again

This part of the process must be down in the command line. Connect to the server console and go to the images directory:

sudo bash

Connect the disk volume as a device

modprobe nbd
qemu-nbd -c /dev/nbd1 /var/lib/libvirt/images/linux-user-vda.qcow2

Now the volume appears as an nbd device in the host system. You can use fdisk and other tools to change the partitions.

Remove and create the partition

First let’s check what are the partitions with fdisk:

fdisk /dev/nbd1

p
Disk /dev/nbd1: 110 GiB, 118111600640 bytes, 230686720 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x88e082d8

Device      Boot   Start      End  Sectors  Size Id Type
/dev/nbd1p1 *       2048   1050623 1048576  512M  b W95 FAT32
/dev/nbd1p2         2048  1126399  1124352   10G 83 Linux

The partition we want to change is the second one (nbd1p2). From fdisk:

# fdisk /dev/nbd1
Command (m for help): d
Partition number (1,2, default 2):
Partition 2 has been deleted.

Now we create the partition again but using all the space we just added. Warning: when asked about remove the signature, answer N.

Command (m for help): n
Partition type
   p   primary (1 primary, 0 extended, 3 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2):
First sector (1126400-230686719, default 1126400):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (1126400-230686719, default 230686719):
Created a new partition 2 of type 'Linux' and of size 109,5 GiB.
Partition #2 contains an ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: N

Then save an exit fdisk:

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Fix the new partition

The new partition must be checked and fixed before resize.

Fix it first in the host:

e2fsck /dev/nbd1p2
resize2fs /dev/nbd1p2

Start

Disconnect the nbd and start the virtual machine.

qemu-nbd -d /dev/nbd1
rmmod nbd

Start the virtual machine from the Ravada frontend as usual.

Check the new size

Boot the virtual machine again, in a terminal type df, it should show the new size.