How-To Geek

Use Drive Mirroring for Instant Backup in Windows 7

Even with the best backup solution, a hard drive crash means you’ll lose a few hours of work. By enabling drive mirroring in Windows 7, you’ll always have an up-to-date copy of your data.

Windows 7’s mirroring – which is only available in Professional, Enterprise, and Ultimate editions – is a software implementation of RAID 1, which means that two or more disks are holding the exact same data. The files are constantly kept in sync, so that if one of the disks fails, you won’t lose any data.


Note that mirroring is not technically a backup solution, because if you accidentally delete a file, it’s gone from both hard disks (though you may be able to recover the file). As an additional caveat, having mirrored disks requires changing them to “dynamic disks,” which can only be read within modern versions of Windows (you may have problems working with a dynamic disk in other operating systems or in older versions of Windows). See this Wikipedia page for more information.

You will need at least one empty disk to set up disk mirroring. We’ll show you how to mirror an existing disk (of equal or lesser size) without losing any data on the mirrored drive, and how to set up two empty disks as mirrored copies from the get-go.

Mirroring an Existing Drive

Click on the start button and type partitions in the search box. Click on the Create and format hard disk partitions entry that shows up.


Alternatively, if you’ve disabled the search box, press Win+R to open the Run window and type in:



The Disk Management window will appear. We’ve got a small disk, labeled OldData, that we want to mirror in a second disk of the same size.


Note: The disk that you will use to mirror the existing disk must be unallocated. If it is not, then right-click on it and select Delete Volume… to mark it as unallocated. This will destroy any data on that drive.

Right-click on the existing disk that you want to mirror. Select Add Mirror….


Select the disk that you want to use to mirror the existing disk’s data and press Add Mirror.


You will be warned that this process will change the existing disk from basic to dynamic. Note that this process will not delete any data on the disk!


The new disk will be marked as a mirror, and it will starting copying data from the existing drive to the new one.


Eventually the drives will be synced up (it can take a while), and any data added to the E: drive will exist on both physical hard drives.


Setting Up Two New Drives as Mirrored

If you have two new equal-sized drives, you can format them to be mirrored copies of each other from the get-go.

Open the Disk Management window as described above. Make sure that the drives are unallocated. If they’re not, and you don’t need the data on either of them, right-click and select Delete volume….


Right-click on one of the unallocated drives and select New Mirrored Volume….


A wizard will pop up. Click Next.


Click on the drives you want to hold the mirrored data and click Add. Note that you can add any number of drives. Click Next.


Assign it a drive letter that makes sense, and then click Next.


You’re limited to using the NTFS file system for mirrored drives, so enter a volume label, enable compression if you want, and then click Next.


Click Finish to start formatting the drives.


You will be warned that the new drives will be converted to dynamic disks.


And that’s it! You now have two mirrored drives. Any files added to E: will reside on both physical disks, in case something happens to one of them.


While the switch from basic to dynamic disks can be a problem for people who dual-boot into another operating system, setting up drive mirroring is an easy way to make sure that your data can be recovered in case of a hard drive crash. Of course, even with drive mirroring, we advocate regular backups to external drives or online backup services.

Trevor is our resident Linux geek, but always keeps his eyes open for neat Windows tricks too.

  • Published 05/25/10

Comments (30)

  1. kwe

    It should be noted that you can also create mirrored drives for any version of Windows and many other OSes by using the software-assisted RAID controllers on many desktop systems. You’ll need to install drivers from the vendor (Intel) and you’ll need a compatible version of their control software, but this approach to mirroring will allow you to mirror your system drive and requires only two compatible drives instead of three separate drives as required in this article.

  2. kzinti1

    Thanks for an interesting, very helpful article. I have a question. I’m using Win 7 Home Premium. I typed in partitions even though you said that the Raid 1 Mirroring feature is unavailable except for Win 7 Pro and above. I haven’t installed anything to make this feature available. I don’t even know to go about it. Do you have any idea how this very nice surprise happened?
    I admit trying some tips that are stated to be irrelevant to my OS just to see what might happen. I wonder if I’ve stumbled upon some way to add some features that aren’t supposed to be compatible with my OS?

  3. Trevor Bekolay

    @ kzinti1

    The Disk Management app is available in all flavours of Windows 7, you just won’t have the option to set up mirrored drives unless you have Pro or above. If you do happen to be able to set up a mirrored drive in Win 7 Home Premium, I’d be very interested to hear about it! You never know what kinds of things slip through on Windows updates.

  4. William

    RAID is not a substitute for a good backup system. It will not protect you from accidental deletion, or from data corruption that doesnt result in drive failure

  5. Justin

    I’m afraid I agree with William. RAID is not a backup. It’s a redundancy solution. All geeks should know this :P

  6. dante

    quick question from a noob, doesnt it mean that when ever u create a file in one drive and mirror drive will also need to spin, which means double the loading time for writing and deleting?

  7. Trevor Bekolay


    There is a slight slowdown, but it’s certainly not double the time to write or delete a file; the drives can both have the data sent to them at the same time, there’s just some overhead in setting up the write/delete operation. In an ideal world, you would actually see some speed-up on reading files (which happens far more frequently than writing files) because you could read data from both drives, but in practice there doesn’t seem to be any speed gains.

  8. dante

    thx for the clear explanation.

  9. Will

    Will this work with 2 different rpm drives? If I have 1 1.5TB 5600rpm drive and 1 1.5TB 7200 rpm drive will this still work?

  10. Trevor Bekolay

    @ Will

    Yes, the RPM of the drive shouldn’t make a difference. However, performance will likely be limited by the speed of the slower drive.

  11. kjay012

    I have used this setup and have 3 partitions on one hard drive being mirrored on another drive. My question is this: If drive D: is being mirrored to a dynamic disk and it fails, what happens? Does Windows 7 automatically switch over to the hard drive with the mirrored image and treat that as drive D?

  12. Hayley

    I’ve recently tried this with two new drives- I go through all the steps, click “yes”, and then it gives me an error message, “The operation is not supported by the object.” What does this mean??

  13. Dangle Berry

    Excellent Article!!! Works a treat!!

  14. Vik007

    What hard drives can you use? Can you use USB drives to setup Mirroring?

    Here it what I want to achieve.

    I want to take a backup on one external USB drive (WD elements drive1) and then mirror that drive to another (WD elements drive2) for duplication. Can this be achieved using the technique explained here?

    Is there any other way to achieve this?

  15. Ara


    I have set C: = G:
    Lets’ say my C: fails due a mechanic problem, can I just swich and place G: and boot from there?

  16. Peter

    I’d like to do the simular to Vik007.
    I want to connect my USB drive to mirror my laptop hard drive. It’s purely there for backup and will have to sync and catch up as I only connect it once a week or so. Is this a crazy idea to be doing?

  17. Henrikus

    How many mirror drives can be created?

    I have 4 partitions I would like to mirror but was only able to create 2 mirror links.

  18. aalex1

    I purchased a large, faster Western Digital drive and want to replace my existing drive. I attempted to mirror the drive using Acronis True Image (WD version) and got a ‘write error” at 75%. This is the second drive that has experienced this problem. I’m using Win 7 Home edition and suspect that Win 7 is preventing the drive mirror process.

  19. Andrew

    i have an HP Pavillion dv7 with a 640GB hard drive which is mirrored. i would like to remove this feature as i will be backing up constantly on an extenal hard drive. what shall i do to remove this mirroring feature? meaning i would like to have the 640GB as 1 hard drive, and not 320GB * 2. please note that i am using ubuntu 10.10. thanks

  20. Christopher

    I do a mirror of my Windows 7 Home Edition once a week. When I get off of work I am going to find out if it works. I am now the proud owner of a rootkit virus and will need to do a full restore.. Guess I should keep my browser where it belongs ;-)

  21. Jeremy Wilson

    “I’ve recently tried this with two new drives- I go through all the steps, click “yes”, and then it gives me an error message, “The operation is not supported by the object.” What does this mean??”

    I’m receiving the same error message. Rosewill USB RS-JBOD enclosure and two 2TB Samsung Spinpoint drives (both unallocated).

    What am I missing?

  22. Christopher Edwards

    I am upgrading to a larger drive. Can I mirror my smaller drive to my larger one and then just take the smaller one out or will it partition the larger drive into two so as to have the same size drive as the smaller mirrored drive?

  23. mian

    hi dear, i have a questoin .i had win vistaon my dell pc optiplex745,my frinnd give me cd of win 7 to install,when i install this it work fine for 1 week but when i am going to install some thing it harddrive crashed and did not boot up,i dont have any back up or rescue cd ,i have a cd that comes with pc but it was to reinstall all the drives,but did not boot my pc to install.i want to make my pc back to default factory setting ,help me to make any cd orplease help me to get out this annoying thing ,pleaseeeeeeeeeeeeee HELP.

  24. Kelly

    I tried to do a mirrored drive setup in Windows 7 Ultimate, get the error message “The operation is not supported by the object.” All steps followed exactly per instructions. Is there something that I’m not doing?

  25. konan

    I had a (windows 7) mirrored setup on my old machine but my motherboard died, I tried plugging in one of the mirrored drives into my new system but I cant see the drive. The hardware wizard found the drive but I was unable to access it, I went into disk management and the disk was labeled “Dynamic foreign” I right clicked and “import foreign disks” and a box popped up with the message B”efore using these disks, add them to your system configuration” I clicked “OK” nothing seemed to happen and in disk manager it just says error next to the disk!
    Can anyone help is there any chance I can recover my data?

    Thanks in advance

  26. Russ

    This question was asked, but I did not see a response. Can I mirror 1 USB drive to another. When I right click on either of the drives, add mirror is not selectable.

  27. robert

    I have a older laptop with Windows 7 Ultimate. It has a 160 gb hd. I bought a 500 gb hd. Can I use this mirror function to mirror the 160 to the 500 and pull he 160 and replace it with the 500 and have the laptop use the 500 as its hd? I tried to mirror the 160 to the 500 and I got this message “This operation is not supported by this object.” What does this mean?

  28. alain

    gr8 article!

  29. Nigel

    Has anyone noticed that there are plenty of articles about setting up a mirrored drive, but just try and find one that tells you what to do if any of the drives fail?

  30. SMK

    Changing a Windows Volume to Dynamic mode is not a very good solution in case of disaster recovery (when suddenly, both drives are failing at the same time or even worse, when the famous NTFS volume becomes RAW all of a sudden!)

    Hardware based raid is a lot faster, reliable and proven. Use wisely!!

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