Latest version of Sun VirtualBox 3.1 under desktop virtualization software came with some new features including Branched Snapshots. Here I explain how branched snapshots works in VirtualBox with examples. If you are familiar with snapshots in earlier VirtualBox versions, it supports you to restore your virtual machine to very recent snapshot only.
For example, if you have three snapshots taken on every week in earlier VirtualBox versions, when your current virtual machine is corrupted or crashed you can restore virtual machine state to last week snapshot only, not to the versions of two weeks or three weeks ago. But in VirtualBox 3.1 with branched snapshots, you can restore your sun VirtualBox virtual machine state to last week, two weeks ago and even three weeks ago. It works backward and forward. This method called branched snapshots in sun VirtualBox 3.1
Still not clear? Lets go little deeper.
Snapshots in Earlier Sun VirtualBox
Snapshots screen look like below in earlier versions, where you can take a snapshot from current state and restore your virtual machine state to just above level (very recent) snapshot.
In the above example, I can restore my virtual machine state to very recent snapshot which is ‘After Joined domain’ only, by right clicking on Current State and select Revert to Current Snapshot.
OK, let’s see if I wanted to restore my virtual machine to one step earlier ‘After Updates’ snapshot.
As you see, when I right click on the snapshot, no options to restore to particular snapshot version. That’s the limitation of earlier versions in VirtualBox.
How Branched Snapshots working in sun VirtualBox 3.1
Let’s see, how branched snapshots in VirtualBox 3.1 works? I have new VirtualBox 3.1 version in different physical computer. So don’t expect to see the same snapshots as shown above. I have windows 2008 server in VirtualBox 3.1 to explain.
Snapshots screen look like below in virtualbox 3.1
If you are running this VirtualBox in earlier versions than VirtualBox 3.1, you have only one option to restore the virtual machine state to very recent snapshot which is ‘ test 23’ in this example. But since VirtualBox 3.1 supports branched snapshots, you can restore to any version of snapshots in VirtualBox 3.1
As you can see, I can cross two earlier snapshots ( test 23 and File server) and restore virtual machine to first snapshot which is ‘After dc (17 days ago)’ by selecting Restore Snapshot. It’s cool, isn’t it?
What will happen to other snapshots when you restore to very first snapshot? Nothing will happen. Those snapshots also remain, and your virtual machine will start running from restored snapshot. Any time you can go back and restore to others version of snapshots. After I restored virtual machine to ‘After dc’ snapshot, my snapshots screen changed as below.
You can see, the current state directly linked to ‘After dc’ snapshot by the line shown by arrow mark. In the earlier picture it’s linked to ‘test 23’. Other snapshot versions also available.
Now I installed several features inside virtual machine windows 2008 to see the difference and how branched snapshots is working. I took two snapshots after some changes inside virtual machine. VirtualBox 3.1 snapshots screen changed as below.
Snapshots started growing like branches, as they called it ‘branched snapshots’. The interesting part is, you can right click on any snapshot and restore your virtual machine state to backward and forward anytime.
Other new feature in VirtualBox 3.1 snapshot is, snapshots have capture of working screen if you take snapshot while virtual machine is working. VMware already got this feature. Sun introduced this in VirtualBox 3.1
As a final test on branched snapshots of VirtualBox 3.1, I restored my virtual machine state to one of earlier snapshot state (File Server snapshot). It’s restored well and worked fine inside virtual machine windows 2008 also. See below snapshot screen.
Current State of virtual machine moved up, and its working from ‘File Server’ snapshot. Other snapshots remain same, and if you are not happy, again you can restore to any snapshot.
I’m sure, this post explains enough on Branched snapshots in VirtualBox 3.1 and how branched snapshots work. Feel free to express your comments and problems you face, so we can solve it and understand the new feature in Sun VirtualBox 3.1 Branched Snapshots.