Sources: https://pve.proxmox.com/wiki/Resize_disks,
I’m writing this down because I do this about every six months and spend a day looking it up and breaking stuff every time. I use LVM and ext4 file system in my VMs.
Expansion Process
```If you enlarge the hard disk, once you have added the disk plate, your partition table and file system knows nothing about the new size, so you have to act inside the VM to fix it.
If you reduce (shrink) the hard disk, of course removing the last disk plate will probably destroy your file system and remove the data in it! So in this case it is paramount to act in the VM in advance, reducing the file system and the partition size. SystemRescueCD comes very handy for it, just add its iso as cd-rom of your VM and set boot priority to CD-ROM.
Shrinking disks is not supported by the PVE API and has to be done manually.”```
1. Resizing guest disk
qm command (or use the resize command in the GUI)
You can resize your disks online or offline with command line:
qm resize <vmid> <disk> <size>
example: to add 5G to your virtio0 disk on vmid100:
qm resize 100 virtio0 +5G
For virtio disks, Linux should see the new size online without reboot with kernel >= 3.6
2. Enlarge the partition(s) in the virtual disk
We will assume you are using LVM on the storage and the VM OS is using ext4 filesystem.
Online for Linux Guests
Here we will enlarge a LVM PV partition, but the procedure is the same for every kind of partitions. Note that the partition you want to enlarge should be at the end of the disk. If you want to enlarge a partition which is anywhere on the disk, use the offline method.
Check that the kernel has detected the change of the hard drive size (here we use VirtIO so the hard drive is named vda)
bash dmesg | grep vda
[3982.979046] vda: detected capacity change from 34359738368 to 171798691840
Example with EFI
Print the current partition table
fdisk -l /dev/vda | grep ^/dev GPT PMBR size mismatch (67108863 != 335544319) will be corrected by w(rite). /dev/vda1 34 2047 2014 1007K BIOS boot /dev/vda2 2048 262143 260096 127M EFI System /dev/vda3 262144 67108830 66846687 31.9G Linux LVM
Resize the partition 3 (LVM PV) to occupy the whole remaining space of the hard drive)
parted /dev/vda (parted) print Warning: Not all of the space available to /dev/vda appears to be used, you can fix the GPT to use all of the space (an extra 268435456 blocks) or continue with the current setting? Fix/Ignore? F (parted) resizepart 3 100% (parted) quit
Example without EFI
Another example without EFI using parted:
parted /dev/vda (parted) print Number Start End Size Type File system Flags 1 1049kB 538MB 537MB primary fat32 boot 2 539MB 21.5GB 20.9GB extended 3 539MB 21.5GB 20.9GB logical lvm
Resize the 2nd partition, first (extended):
(parted) resizepart 2 100% (parted) resizepart 3 100%
Check the new partition table
(parted) print Number Start End Size Type File system Flags 1 1049kB 538MB 537MB primary fat32 boot 2 539MB 26.8GB 26.3GB extended 3 539MB 26.8GB 26.3GB logical lvm (parted) quit
3. Enlarge the filesystem(s) in the partitions on the virtual disk
If you did not resize the filesystem in step 2
Online for Linux guests with LVM
Enlarge the physical volume to occupy the whole available space in the partition:
pvresize /dev/vda3
List logical volumes:
lvdisplay
--- Logical volume ---
LV Path /dev/{volume group name}/root
LV Name root
VG Name {volume group name}
LV UUID DXSq3l-Rufb-...
LV Write Access read/write
LV Creation host, time ...
LV Status available
# open 1
LV Size <19.50 GiB
Current LE 4991
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
I’ve noted that in Ubuntu Server the Volume Group Name does not end in root as Ubuntu Desktop does.
Here is Ubuntu Server
--- Logical volume --- LV Path /dev/ubuntu-vg/ubuntu-lv LV Name ubuntu-lv VG Name ubuntu-vg LV UUID DoMD3y-0lmV-osy5-mwOj-hMs9-ruaV-S8ufTu LV Write Access read/write LV Creation host, time ubuntu-server, 2022-01-24 21:59:57 +0000 LV Status available # open 1 LV Size <66.00 GiB Current LE 16895 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0
and here is Ubuntu Desktop (Ubuntu Mate)
--- Logical volume --- LV Path /dev/vgubuntu-mate/root LV Name root VG Name vgubuntu-mate LV UUID Z270jO-SCGC-cttK-Vtac-m2gF-zILg-dPA9xO LV Write Access read/write LV Creation host, time ubuntu-mate, 2023-11-19 18:59:16 -0500 LV Status available # open 1 LV Size <55.77 GiB Current LE 14276 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 252:0
Enlarge the logical volume and the filesystem (the file system can be mounted, works with ext4 and xfs). Replace “{volume group name}” with your specific volume group name:
This command will increase the partition up by 20GB
lvresize --size +20G --resizefs /dev/{volume group name}/root
Use all the remaining space on the volume group
lvresize --extents +100%FREE --resizefs /dev/{volume group name}/root
Online for Linux guests without LVM Enlarge the filesystem (in this case root is on vda1) An ext4 file system may be grown while mounted using the resize2fs command:
resize2fs /mount/device size
resize2fs /dev/vda1
Other useful commands and their output
fdisk -l Disk /dev/vda: 67 GiB, 71940702208 bytes, 140509184 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: gpt Disk identifier: D1A6933C-7817-4756-AA1B-5D924F3054B0 Device Start End Sectors Size Type /dev/vda1 2048 4095 2048 1M BIOS boot /dev/vda2 4096 2101247 2097152 1G Linux filesystem /dev/vda3 2101248 140509150 138407903 66G Linux filesystem Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 66 GiB, 70862766080 bytes, 138403840 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
lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS loop0 7:0 0 1.9M 1 loop /snap/bottom/759 loop1 7:1 0 4K 1 loop /snap/bare/5 loop2 7:2 0 1.9M 1 loop /snap/btop/655 loop3 7:3 0 9.6M 1 loop /snap/canonical-livepatch/246 loop4 7:4 0 105.8M 1 loop /snap/core/16202 loop5 7:5 0 63.9M 1 loop /snap/core20/2105 loop6 7:6 0 74.1M 1 loop /snap/core22/1033 loop7 7:7 0 152.1M 1 loop /snap/lxd/26200 loop8 7:8 0 40.4M 1 loop /snap/snapd/20671 vda 252:0 0 67G 0 disk ├─vda1 252:1 0 1M 0 part ├─vda2 252:2 0 1G 0 part /boot └─vda3 252:3 0 66G 0 part └─ubuntu--vg-ubuntu--lv 253:0 0 66G 0 lvm /
growpart /dev/sda 3
pvresize /dev/sda3
lvextend -l +100%FREE /dev/pve/root
resize2fs /dev/mapper/pve-root