How can size of the root disk in Google Compute Engine be increased?

Question 1

As of 31 Mar 2016, you can resize a persistent disk online without stopping or rebooting the VM, without taking snapshots, and without having to restore it to a larger disk.

The blog post announcing the feature has the details, and you can see the docs for how to do this via the console:

Resize the persistent disk in the Google Cloud Platform Console:

Click on Compute Engine product tab.

Select Disks under the "Storage" section.

Click on the name of the disk that you want to resize to get to the disk details page.

At the top of the disk details page, click "Edit".

In the "Size" field, enter the new size for your disk.

At the bottom of the disk details page, click "Save" to apply your changes to the disk.

After you resize the disk, you must resize the disk partitions so that the operating system can access the additional space.

Or via CLI:

gcloud compute disks resize example-disk --size 250

Then, on Debian/Ubuntu/etc. run:

$ sudo apt install -y cloud-utils         # Debian jessie
$ sudo apt install -y cloud-guest-utils   # Debian stretch, Ubuntu
$ sudo growpart /dev/sda 1
$ sudo resize2fs /dev/sda1

or, for RedHat/Fedora/CentOS/etc.:

$ sudo dnf install -y cloud-utils-growpart
$ sudo growpart /dev/sda 1
$ sudo xfs_growfs -d /                    # CentOS 6 needs `resize2fs`

Note that some operating systems will automatically resize your partition on reboot without requiring you to do any manual steps with tools such as fdisk, resize2fs or xfs_growfs, so it should be sufficient to just resize the disk and reboot the VM for changes to take effect.

Question 2

create a new disk from snapshot, but increase the size when doing so
create a new instance, using new, embiggened disk
embiggen the partition to recognize the new space (https://cloud.google.com/compute/docs/disks/persistent-disks#repartitionrootpd) (NOTE: pay special attention to the starting sector, don't just blindly hit return, you can, however blindly hit return on the ending sector)
sudo resize2fs /dev/sda1 (note, this step is not mentioned in the google cloud docs)

Question 3

In most cases, it will be simpler and more flexible to create a second data disk of the size you want, and attach it to the instance.

To resize a Persistent Disk (including a root disk), snapshot the disk, then create a new larger disk from the snapshot.

Question 4

This is more like a follow-up to @user1130176's answer, but if you are running CentOS 7+, you'll need to do the following for step #4 (expanding the filesystem): xfs_growfs /dev/sda1

The new disks on CentOS 7 are of type xfs. Hope this helps, it was not very clear from all the links around.

Question 5

Since the new GCoud command line tool you can choose your boot disk size and type at the instance creation:

gcloud compute instances create foo-instance --boot-disk-size 100 --image "xxxxxx"

Then resize the root partition using these instructions: https://cloud.google.com/compute/docs/disks#repartitionrootpd

Documentation : https://cloud.google.com/sdk/gcloud/reference/compute/instances/create

Edit: After resizing the root partition, you have to reboot your instance to force the system to re-read the partition table. That makes this trick unusable in a startup script (executed on each startup/reboot).

Question 6

I know this is an old topic, but I just did this using a simpler method than the ones explained above. All from the cloud console user interface with no need to worry or do any special commands in just a few minutes and clicks.

However, it requires creating a new instance, not resizing a disk on an already running instance

Create a snapshot of the disk you want to enlarge

Click on the instance, then click on the disk, then you have "create snapshot", give it a name and then wait for the snapshot to be created. (You don't need to turn off the instance for this)
Create a new instance from the snapshot and specify the new size

Click on the snapshot, then you have "create instance", you can then see the boot disk options, click change and then size it to a new size. (You probably want to change all the default instance settings to the ones you want also)

This is a fool-proof way to enlarge a disk without causing any partition errors, doesn't require any commands or special actions.

The only downside is that you need to create a new instance. You can't just do it on an instance that you already have.

Question 7

Now you can resize a Persistent Disk in place:

gcloud compute disks resize DISK_NAME [DISK_NAME …] --size SIZE [--zone ZONE]

This would only re-size physical device. file system (and possibly partitions still need to be adjusted after that)

Question 8

Create a disk first with whatever size and image you want, and then create your instance using Existing Disk as your boot source.

Question 9

For anyone else unable to find a working answer, I found this script someone kindly posted:

https://gist.github.com/xelwarto/6f5c6556613c9215b1e1

# Requires cloud-utils-growpart to be installed

# Resize ROOT FS
part=`df --output=source / |grep "/dev/"`
if [ ! -z "$part" ] ; then
  len=${#part}
  p=`echo $part|cut -c$len`
  d=`echo $part|cut -c1-$(($len-1))`

  growpart "$d" "$p"
  xfs_growfs "$part"
fi

Question 10

now its has changed the command , always better to follow Google Documentation. as of Sep 2nd 2022.

https://cloud.google.com/compute/docs/disks/resize-persistent-disk

Before resize disk:-

mgadage8@vm:~$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 30G 0 disk ├─sda1 8:1 0 9.9G 0 part / ├─sda14 8:14 0 3M 0 part └─sda15 8:15 0 124M 0 part /boot/efi mgadage8@vm:~$ df -h Filesystem Size Used Avail Use% Mounted on udev 1.8G 0 1.8G 0% /dev tmpfs 368M 368K 368M 1% /run /dev/sda1 9.7G 1.7G 7.5G 19% / tmpfs 1.8G 0 1.8G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock /dev/sda15 124M 5.9M 118M 5% /boot/efi tmpfs 368M 0 368M 0% /run/user/1000