Fortunately, the times when a PC or server could have only one operating system are the history long forgotten: at present, whether you’re a professional software developer who needs to test his/her app on multiple platforms, or an ordinary home user who wants to install a program which appeared to be not compatible with the OS your PC or Mac runs on, with the help of virtualization, you can employ as many operating systems on a single machine as you wish (if its capacity allows, of course). These operating systems can run side-by-side managed by a piece of special software called a hypervisor, or one operating system will run the others. Moreover, virtual machines are widely used for increased fault tolerance and security, for sharing hardware resources and thus improving efficiency and reducing costs as well as for testing new configurations, upgrades and software. But contrary to the popular belief, a virtual machine is no way immune to data loss and, what is more, such an unpleasant surprise may be encountered at any time.
Despite acting like a real separate computer with its own operating system, in reality, a virtual machine is just a single giant file. Its CPU, RAM, ROM, video card and all other components exist only as bits and bytes, and those guys can easily get corrupted. Moreover, in addition to using the hardware resources of their physical hosts, VMs inherit their main vulnerabilities: A total failure of the hard drive or RAID the virtual machine resides on inevitably affects its data. In fact, a wide range of factors may render the files stored on a VM inaccessible:
Mistakenly deleted files/folders/partitions and accidental formatting
In spite of its “virtuality,” a VM has actually the same contents as a conventional physical hard drive, including a file system, disk partitions, folders and files. In similar fashion, any of these can be accidentally deleted due to a user mistake. Furthermore, the entire virtual machine can be unintentionally formatted which will apparently result in the loss of all files stored on it. Luckily, the data lost from a VM you awfully need back is not gone forever. Having been deleted, those files are no longer available for read or write operations, but, in fact, the sectors they occupy are not erased and just get marked as available for new files, therefore, with the right approach, there is always a chance to bring them back.
Malware attacks and other kinds of logical mishaps
Just like with physical hard drives, data stored on a virtual disk is constantly at risk of getting lost or damaged owing to some logical issues, such as virus attacks, corruptions within the file system, software-related problems and numerous other factors. This type of failure may even cause the whole VM to show inaccessible, preventing the user from opening any file it contains.
Deleted virtual machine or its configuration
On account of the fact that any file on the computer can be deleted in several clicks, so can virtual machines. However, by a twist of fate the user may happen to delete the wrong virtual machine, or just click on the remove button by mistake. Critical VM configuration files, when mistakenly deleted, are also one of the possible causes of catastrophic data loss.
Similar to any desktop or laptop computer, a virtual machine is based on real hardware, i.e. uses a physical storage to store its operating system, applications and data files. It can be a singe hard disk drive or SSD as well as several disks organized into a RAID system, which can easily fail in view of their mishandling, power surges, natural disasters or even age. But the problem is that a failed physical storage device leads to a cascading failure of the all virtual and physical machines residing on it. Do not leave failing or failed hardware powered as it will increase the likelihood of further data damage. If your important VM files fell victim to a disk failure, this is the worst-case scenario and only a certified technician can do the all the needed repairs and carry out the recovery procedure.
Thankfully, if the storage device didn’t undergo severe physical damage that left VM files inaccessible or lost, proper tools allow anyone to perform DIY data recovery even from a virtual environment. To start the rescue operation, you just need to download and install data recovery software that supports virtual disk recovery on your computer. Nevertheless, even a minor mistake made in this process may cost you all your precious files.
First and foremost, the sooner you realize that the data is missing, the better. It is highly important that you should immediately shut down your virtual machine since if you keep using it, those lost files can be easily overwritten. Even temporary files or cache that may be written to the storage while it is working and significantly reduce the chances of successful recovery. Also, do not delete any additional files as this may also hinder a positive outcome.
Secondly, in case if you have other active virtual machines on the same volume as the problem one, shut them down as well. Those that cannot be shut down during the recovery should be cloned to another volume, but do not migrate them since they may be then found as a part of lost data by recovery software.
Moreover, do not run any file system repair tools (like FSCK or CHKDSK) on the problem virtual machine before you’re absolutely sure that all the needed files have been recovered or a good backup has been made and saved to a different volume. These utilities are likely to overwrite the lost files in their attempt to repair corrupt file system structures.
Also, it is not recommended to try using any data recovery software unless you are completely certain that it will not write anything to the disk which needs to be restored. A quality data recovery tool should be able to load a virtual disk without running the VM and retrieve the missing files from the loaded virtual disk.
On the whole, it is a very common misconception that virtual machines are essentially safer from data loss than physical storage media. In truth, massive switch to virtual environments doesn’t make data loss the thing of the past, and even contributes to it for few people know that they should take preventive measures to protect their virtually stored files. But fortunately, when a virtual data loss disaster strikes, the ship hasn’t sailed until the lost files are overwritten as with the right knowledge and software they have good chances to be recovered.