How to Shrink a VirtualBox Virtual Machine and Free Up Disk Space

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By default, VirtualBox creates dynamic disks that grow over time as you add data. However, if you delete data from the virtual machine later, you’ll notice that the disk doesn’t automatically shrink. But you can manually shrink a dynamic disk using a hidden command.

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Remember that this will only shrink the disk if it’s grown in size and you’ve since removed data. So, if you just created a dynamic disk, this won’t shrink it. But, if you’ve created a dynamic disk, downloaded 10 GB of data into it, and then deleted that 10 GB of data afterwards, you should be able to shrink the disk by about 10 GB.

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https://www.howtogeek.com/312883/how-to-shrink-a-virtualbox-virtual-machine-and-free-up-disk-space/

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