How to shrink a dynamically-expanding guest virtualbox image | dantwining.co.uk

How to shrink a dynamically-expanding guest virtualbox image | dantwining.co.uk:



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This worked for me on Debian Testing which has a habit of increasing in size purely due to the number of updates required.



I first tried compacting the disk without zeroing the space and the disk size went down from 12.485GB to 12.476, a massive 9MB saving. ;)



I then followed the procedure in the post modified slightly for Debian:

1. Install zerofree using 'sudo apt install zerofree'
2. Power off the virtual system using 'sudo poweroff'
3. Boot the system holding left shift
4. Select advanced options
5. Select recovery mode using the latest installed kernel
6. Identify your root filesystem (and any other filesystems you want to compact) using 'mount'; take a note of the filesystem type they are using as well
7. 'service rsyslog stop'
8. 'service network-manager stop'
9. Run the following two commands for all the required filesystems:
1. 'mount -n -o remount,ro -t ext4 /dev/sda1 /'
2. 'zerofree -v /dev/sda1'
3. Replace ext3 with the required filesystem type, / with the required mount point, and /dev/sda1 with the required device
10. 'poweroff'
11. Compact the files system using cmd prompt if on Windows:
1. 'cmd' (run as administrator)
2. 'C:'
3. 'cd "\Program Files\Oracle\VirtualBox"'
4. 'vboxmanage modifyhd "D:\VMs\Debian Testing\Debian Testing.vdi"' (replace the .vdi path with our own disk image)

My Debian testing disk image was then reduced to 7.333GB saving a further 5.143GB or 41% of the total space.