Cannot change VM root disk size

LXD
1

I’m following Running virtual machines with LXD 4.0 to start an Ubuntu Focal VM.

I then run the following to get more CPU and RAM (as a tangent, the listed defaults on https://linuxcontainers.org/lxd/docs/master/instances are wrong).

lxc config set banana limits.cpu 8     
lxc config set banana limits.memory 8GB

I can see these reflected once I start the VM. However, I also run

lxc config device add banana root disk pool=default path=/ size=100GB

but this isn’t reflected inside the VM

root@banana:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            3.7G     0  3.7G   0% /dev
tmpfs           741M  688K  740M   1% /run
/dev/sda2       3.8G  730M  3.0G  20% /
tmpfs           3.7G     0  3.7G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           3.7G     0  3.7G   0% /sys/fs/cgroup
/dev/sda1        99M  3.9M   95M   4% /boot/efi
config          9.4G  8.0M  9.4G   1% /run/lxd_config/9p

I’m using ZFS as the pool provider.

2

Unlike containers, VMs use block devices that are not managed by LXD itself, so you need to update and grow your partitions in the VM.

cat /proc/partitions will show the full block size, then use something like growpart to resize your partition table and partitions.

2 Likes
3

I have also tried to set this in the profile:

  root:
    path: /
    pool: default
    size: 100GB
    type: disk

It also gives me the same 3.8GB root.

4

Thanks, I’ll try that now.

5

@stgraber is there another step I need to do (I’ve tried rebooting)?

root@banana:~# cat /proc/partitions 
major minor  #blocks  name

   8        0   97656248 sda
   8        1     102400 sda1
   8        2    4090863 sda2
   8       16        356 sdb

root@banana:~# growpart /dev/sda 2
CHANGED: partition=2 start=206848 old: size=8181727 end=8388575 new: size=195105615 end=195312463

root@banana:~# cat /proc/partitions 
major minor  #blocks  name

   8        0   97656248 sda
   8        1     102400 sda1
   8        2   97552807 sda2
   8       16        356 sdb

root@banana:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            3.7G     0  3.7G   0% /dev
tmpfs           741M  696K  740M   1% /run
/dev/sda2       3.8G  839M  2.9G  23% /
tmpfs           3.7G     0  3.7G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           3.7G     0  3.7G   0% /sys/fs/cgroup
/dev/sda1        99M  3.9M   95M   4% /boot/efi
config           94G  7.0M   94G   1% /run/lxd_config/9p
6

In case anyone else has this issue, you need to run resize2fs /dev/sda2 after growpart /dev/sda 2

5 Likes
7

Script to do this here https://gist.github.com/joedborg/2ad747923104273c79dda76fe5063ce2

1 Like