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How To Mirror Copy a Hard Drive

written by: Steve McFarlane•edited by: Simon Hill•updated: 5/30/2010

In this article we look at some of the reasons for creating a mirror copy of a hard disk and how to accomplish the mission.

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    Mirror Copy

    Creating a mirror copy of a hard disk is often done to transfer an operating system and data files in their entirety to another computer, or to create a computer backup. The process may involve using a software package to clone a disk or using a hardware solution such as RAID.

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    Use a Hard Drive Cloning Software

    Hard drive cloning software such as True Image and EASEUS can be used to create a perfect image of a hard drive that would include user documents, system files and boot instructions.

    This solution is ideal for:

    • Creating a 100% identical copy of the original for data recovery purposes.
    • Upgrading from a small hard drive to a larger one without losing configuration settings, user data, or having to reinstall the operating system. Except for a change in storage capacity and performance, the hard drive clone shouldn’t look or behave any different from the original.
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    Some Points of Caution Regarding Cloning Disks

    Before proceeding with the disk copy procedure, be very confident that the destination and source disk are correctly identified. Failing to do so may result in the wrong disk being over written. Here are some other things that must be considered before proceeding with the disk copy process.

    • The destination disk can be of a lesser capacity than the source disk. However, the destination disk must have enough space to take all the files from the source disk or else the disk mirroring process will fail.
    • Most, if not all, disk cloning software will erase all data from the destination disk.
    • Generally speaking, the boot disk cannot be the destination disk.
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    How To Mirror Copy a Hard Drive

    There are some disk cloning software packages that will run in a GUI interface such as Windows, and in other cases they will need to run outside the OS after being started from a boot disk. The process will differ from one cloning tool to another but the process should proceed as follows:

    • Start the disk clone softwareHow To Mirror Copy a Hard Drive 
    • Start cloning wizard
    • Identify and set the destination and source disk
    • Hit the start button and wait for the process to be completed
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    RAID Level 1 Hard Disk Mirroring

    In situations when data security is a high priority, and up to the minute backups are required, a RAID solution can also be used to create and maintain a mirror copy of a hard disk. RAID technology uses no less than five separate schemes, known as RAID levels, to improve hard disk performance, data security, and data availability.

    Originally there were five schemes but several blends of these schemes have created other variations. The one we are interested in is RAID level 1 (mirroring without parity or striping). Level one increases fault tolerance by writing identical data to multiple hard disks on an ongoing and constant basis. In essence, several hard drives act as mirrors of the others in the RAID configuration. This is a perfect way to ensure that a mirror copy is always available just in case a drive, from the array, fails.

    If one or several drives in the RAID fail, the system will simply use copies on the remaining hard disks. Except for alerts that one or several disks have failed, users should notice no change in data or system availability unless all the drives fail.
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    While software backup tools can be used to manually create backups of a hard disk, this process is not as reliable or comprehensive for copying the contents of the source disk, which includes: hidden files, system files, partitions and even deleted files that are recoverable. Not only can disk clones provide a data recovery option, but they also provide a way to transfer an entire OS and data files to a new hard drive or computer.

    To create a 100% identical copy of a hard drive, it is best to use a RAID solution to provide ongoing and backups or a software-cloning package to do a one-time mirror copy.


    Image: "How To Mirror Copy a Hard Drive." Jeff Kubina