Although backup and disk mirroring are often used interchangeably, a mirror is decidedly not a backup. Mirroring and backups serve different purposes. A mirror is designed to keep your system up and running in the case of a hard disk failure. While a backup essentially serves that purpose, it is designed to provide you with data protection should a file, folder or an entire disk drive fail.
Let’s say you have a system with two 500 GB drives configured in a RAID 1 mirror. Any data written to one drive is automatically duplicated to the other. This is great if you are concerned that you might be susceptible to a disk drive failure. Should your primary hard disk fail, all you need do is move the mirror into the primary drive’s position and keep going. But mirrors come with their own set of issues. Let’s say your antivirus or antimalware software allows an infection to get by. Now you have a problem on both your primary drive and the mirror. Mirrors let bad things happen much faster.
Now let us assume that you are backing up your primary drive with either a file- or image-based backup software and your primary drive gets a virus. You have options. If you have a file-based backup, you need only to clean the primary drive and then copy the cleaned files to your backup. This is the same technique you would use for backups to cloud-based backup environments.
If you back up using sector-based disk images backed up to local drive or network-attached storage device and your image becomes infected, simply mount your image as a virtual disk in read/write mode. Run your antivirus software against the mounted image and clean the virus. Once that’s done, save the image as an incremental backup and your image will be clean.
Some computers ship from the manufacturer with a preconfigured disk mirror. Don’t be mislead that you have a preconfigured backup; you don’t. There are a variety of RAID configurations that are designed to protect data, but each serves a different purpose. For RAID 1, the disk mirror, the purpose is protection from a failed hard disk.
Mirroring is not Backup
Standard by Hamzeh Tabbaa February 17, 2011 No Comments