Increase the Stateful Partition Size of Chrome OS Flex Live USB

When you create a Chrome OS Flex live USB drive using the official Chromebook Recovery Utility extension, you might notice a frustrating limitation: the recovery image doesn’t utilize the full capacity of your USB stick. If you’re using a 64GB or 128GB USB drive, Chrome OS Flex might only use a small portion of that space, leaving the rest inaccessible.

This becomes particularly problematic when you want to install Linux applications or store additional files on your Chrome OS Flex system, as the limited stateful partition quickly runs out of space.

The Solution: Manual Partition Expansion

There’s a way to expand the Chrome OS Flex image before flashing it to your USB drive. This process involves modifying the recovery image file to utilize more of your USB drive’s capacity.

Steps

1. Download the Chrome OS Flex Recovery Image

First, obtain the official Chrome OS Flex recovery image:

• Visit: https://chromiumdash.appspot.com/serving-builds?deviceCategory=ChromeOS%20Flex
• Download the recovery image

2. Prepare Your Linux Environment

Open a Linux terminal (or WSL2 if using Windows) and navigate to the directory containing your image file:

cd /path/to/your/image/directory

3. Expand the Image Size

Use the truncate command to increase the image file size. This adds free space that we can later allocate to partitions:

truncate -s +50G chromeos.bin

Note: Replace chromeos.bin with your actual image filename. Adjust 50G based on your needs and USB drive capacity.

4. Set Up Loop Device

Create a loop device to work with the image file as if it were a physical disk:

sudo losetup -Pf chromeos.bin

5. Identify the Loop Device

Find out which loop device was assigned:

lsblk

Look for entries like loop0, loop1, etc. Note the device name for subsequent commands.

6. Repair the GPT Partition Table

Check the current partition table status:

sudo cgpt show /dev/loop0

Note: Replace loop0 with your actual loop device name.

If you see “Invalid info” or similar errors, repair the partition table:

sudo cgpt repair /dev/loop0

7. Fix Partition Table Issues with gdisk

Use gdisk to ensure the partition table is properly structured:

sudo gdisk chromeos.bin

Within gdisk, execute these commands:

• Press p to print the partition table
• Press x to enter the expert menu
• Press e to access extra functionality
• Press w to write changes and exit

8. Expand the Chrome OS Flex Partition

Use cgpt to modify partition 1:

sudo cgpt add -i 1 -s 83886080 /dev/loop0

Important: The value 83886080 represents approximately 40GB in sectors. Adjust this value based on your desired partition size. You can calculate sectors by: desired_size_in_GB × 1024 × 1024 × 2

9. Verify the Changes

Confirm that the partition has been expanded correctly:

sudo cgpt show /dev/loop0

10. Repair and Resize the Filesystem

Check the filesystem for any issues:

sudo e2fsck -f /dev/loop0p1

Resize the filesystem to use the newly allocated space:

sudo resize2fs /dev/loop0p1

11. Clean Up

Detach the loop device:

sudo losetup -d /dev/loop0

If you have any mounted partitions, unmount them:

sudo umount /path/to/mountpoint

12. Create the Bootable USB

Now you can create your bootable USB with the expanded image:

1. Insert your USB drive
2. Open Chrome browser
3. Launch the Chromebook Recovery Utility extension
4. Click the settings icon (gear icon in the top right)
5. Select “Use local image”
6. Browse and select your modified Chrome OS Flex image
7. Select your USB drive as the target
8. Start the recovery process