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Optimising your windows virtual machine (Oracle Virtualbox)

My windows virtual machines vdi disk images were hitting over 35GB a piece, the following notes are a reminder of the steps required to shrink the VDI’s when they get oversized.

Clean up your VM

First – get rid of anything surplus to requirements, recycle bin, disk cleanup, the usual suspects.

Run defrag.

Download the Microsoft tool – sdelete and stick it in System32 – then open CMD and for each drive you are using run – (note the official documentation is wrong!)

sdelete -z

Now if like me you have set a high upper limit to your drive size prepare for a long wait… and make sure that your machine has enough space available to accommodate the full-sized HDD image as this command will expand the image whilst it’s being zeroed out.

And shrink

From the host environment you can then run –

VBoxManage modifyhd Disk.vdi --compact

Refs – official, at the time or writing the instructions are not correct… Oracle page

Oracles bug tracker regarding issues resizing Oracle tracker



Craig enjoys producing usable and friendly sites that look great and function well. He often also experiments with workflow automation and owns and runs web-engineer.

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