VirtualBox - Clone vs Snapshot vs Backup

Question

Looking for a simple answer to some virtualbox options.. What are the differences between Clone & Snapshot & Backup? Which should be used when?

I've just started with virtualbox & have Ubuntu running on OS X as host.

Basically i have setup Android SDK & ADK and other tools. Just before i start building, i want to have a "backup" where if anything goes wrong, i can just revert to this instance of a clean installation. Previously i had a situation where Ubuntu locked me out completely & i was unable to do much other than a complete re-install.

Would it be just alright to have a snapshot & revert to this snapshot if something goes wrong? Or would i need a clone of it? or both? and to backup, is it just sufficient to have a copy of the folder alone?

thanks

Answer 1

Clone: Duplicates your VM. It can be a linked clone referenced to your original VM via a snapshot, or it can be a full clone. You can create a clone to compact your disk image like VMware's Compact tool: use your virtualized OS to fill your free space with zeroes (Eraser Portable on Windows, cat /dev/zero > ~/dsfargegfgsfds then rm ~/dsfargegfgsfds on Linux), delete any temporary files, and clone your VM; the new disk image will be created without the zeroed-out free space.

Snapshot: A kind of restoration point. When you create a snapshot VirtualBox will start saving new writes to the virtual disk to a differential image, when reading it will take into account the differential image as well as the drive. When you restore a snapshot you're basically telling VirtualBox to ignore the snapshots that don't lead to the specified restoration point.

Export: A packaged archive that contains your VM's hard drive image and configuration.

In my experience VirtualBox is a flimsy and fickle program that can fail unexpectedly in terrible ways (right now I'm trying to rescue a disk image that corrupted due to a program crash), so back up very often. Back in college I must have accumulated like 25 GB of VM backups out of a VM that was, like, 2 GB tops, because for every single little thing I had to export my progress or risk losing days of work and missing an assignment deadline.