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How Do I Test Backups?

Three practical steps to make sure the safety net will work.

It's a good idea to test backups before disaster strikes. Unfortunately, a complete test can be risky. I'll look at some alternatives.
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Question: I back up my data using Windows, but it’s not maybe as retrievable as I would like it to be. I don’t know exactly how to test backups to know whether they’re really there. It says they are, but are they? I’ve had to use the system image to restore function once when my computer became infected with something. I basically just transferred the system image back to my C drive and it solved all my problems. I must say I’m thankful to you for strongly encouraging everyone to do backups. I can’t tell you how many friends and family have lost stuff – everything – because of not backing up. Pictures, important data. Loss of pictures seems to be the most heartbreaking.

Yeah, I hear those heartbreaking stories all the time, and they are indeed one reason I talk so much about backing up.

Your concerns about backups are common, as is the desire to test.

Let’s review how you can gain some confidence that your backup will be successful when you need it.

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Testing backups

  • A full restore is the ultimate test, but is typically impractical to carry out.
  • Test the rescue media by booting from it and preparing for a restore, but stop before it starts.
  • Test a backup image by restoring individual files from one.
  • Test a backup image by viewing its contents and making sure all expected files are present.
  • You can perform a complete test by replacing the hard drive and restoring an image.

A full restore is the ultimate test

The ultimate way to test backups, of course, is exactly what you ended up doing: performing a full restore of an image backup.

A full restore is the most important to have work, since it’s what can save you from almost any problem. Malware infection? Restore to an image created before the infection, and it’s gone. Disk failure? Replace the drive, restore the most recent image, and you’re up and working again.

The problem for testing backups is that a full restore is really, really risky.

By definition, a full restore is a destructive operation. It erases what’s currently on the hard drive and replaces it with the contents of the backup image. If the restore fails part way through, you’re worse off than when you began. You found out your backup didn’t work, but you trashed what was on the hard drive in the process.

The very restore you took to be able to fix the failure is the restore your test just discovered doesn’t work!

Here’s my approach to testing backups.

1. Use the rescue media, prepare for a restore, and stop

Create the rescue media — sometimes called an “emergency disk” — from your backup program. This is the CD, DVD, or USB stick you would boot from in order to perform that full restore. Then boot from it.

Getting this to work is important, because booting from something other than your hard drive can be complicated, particularly in newer machines.

Once the software from the rescue media is running, make sure it can see the drive that contains your backup images.

Then follow the steps to do an image restore, stopping at the very last step before the restore would begin. This verifies that your recovery disk works and the backup program can access what’s necessary to perform the restore.

That’s about as far as you can go without actually performing the restore, but it’s tested quite a bit.

2. Extract files

Most backup programs allow you to extract individual files from your full system backup image. Doing so is another way to test backups.

I recommend restoring a single file.

Exactly how to do this varies depending on the backup program you’re running, but the scenario is the same: delete or rename an unimportant file on your hard disk and go through the steps for your backup program to restore the file from a backup.

You shouldn’t need to boot from the rescue media. This is something you should be able to do by running the backup software and using it to extract individual files from wherever your backups are stored.

If you succeed, great! You now have confidence the files contained in that backup image can be restored in the event of a disaster.

If you fail, however, you know you need to revisit how you’re backing up to make sure you’re backing up what you need in the appropriate way.

3. Check the image

There’s one final test to make sure the files you think are in your backup are in fact in your backup.

For example, in my Maximum Reflect course, I outline how to mount a backup image as a virtual hard drive. You can do this with Windows backup and other backup programs as well. You can then examine the contents of the image to make sure it contains what you expect.

Poke around in the backed-up Windows folders to make sure all of Windows is there. Browse through the folders that contain your data to ensure the same. Look around inside that image to ensure it has what you might need should the worst happen.

There is no 100% guarantee that your backup will work when you need it, but these tests can give you confidence that common issues that often get in the way of an effective backup won’t get in the way for you.

4. A complete test, done safely

There’s one more way to test backups. It involves more work and some additional cost, but it’ll prove beyond a doubt that your backups work.

  1. Buy a new hard drive.
  2. Replace the hard drive in your machine with the new hard drive.
  3. Restore an image to the new hard drive.
  4. Reboot.

If this works, you can leave the new hard drive in your machine and keep the old as a spare.

If it fails, you simply put the old hard drive back in your machine, and move on to diagnose how your backup failed and why.

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46 comments on “How Do I Test Backups?”

  1. Here’s a scenario that might work. When my hard drive died, I installed a new SSD in my computer. I didn’t restore from my backup because I wanted to install Windows 8.1 as I had a license for it already. Now after taking out the old drive, and placing it in a USB housing, it appeared to be OK, so I tried restoring from my backup to that external drive, mostly just out of curiosity. Macrium got about halfway through the restore when it errored out because the external drive really was defective. Now my question is whether this would be another ultimate test of a backup, by restoring it to an external drive. And would that drive be bootable if created that way? I didn’t have time to test it again with a good external drive, but it seems like it should work as there wouldn’t be much difference between an external disk and an internal disk on a system booted from a CD.

    • I believe it depends on a lot of details, but in theory I believe that the answer is yes – if you restore the entire backup (including MBR, partitions and such) to the external drive that should make it bootable. It just may not be bootable *as* an external drive. By that I mean you may need to then reinstall it in the machine as it was before when the backup was taken.

  2. This is a major problem with image backups. You are never 100% certain they worked. On the other hand, with a bootable file by file clone/copy, you merely change the boot sequence and boot to the backup. Simple, effective, and only takes a minute.

  3. my solution to testing the integrity of the desktop backups I make on a regular basis is:

    1] install a second internal HD (HD2) but don’t connect the sata cable
    2] make and validate the image of the current HD (HD1)…. (I use Acronis).
    3] Pop the PC cover, remove the sata cable from HD1 and install to HD2
    4] boot the PC with the acronis rescue disks
    5] restore the image to HD2
    6] reboot and use HD2 as the operating disk

    When it comes time to make and restore the next image, just switch the sata cable back to HD1 and follow the same steps. This method accomplishes two things:
    1] it provides 100 % assurance that the image can be restored
    2] It provides one with a fully functional “spare HD”

    One might argue that switching the sata cable around is a bit of a pain. The procedure is simple and takes only a minute or two to complete, which I believe is a very small price to pay for what is accomplished.

  4. I agree with all Leo says on the subject, but like to add this: in parallel to image backups with Macrium etc. it is a good idea to make extra backups of your data on one or more external small disks (300GB drive with usb-interface for instance):
    – projects at hand,
    – personal photos,
    – email history,
    – anything else you never want to lose.
    The key to simple management of these data is to keep them well-organized in one or a few directories. For each backup you just create a new directory on the external disk, e.g. BU_ABCD_yymmdd, where ABCD is your computer ID (so you can backup data from more than one machine on the same disk), and use the file explorer to copy the directories into it.
    It’s fast, simple, effective, and you have the data in the original format, the same format they have on your machine.
    I recommend this not as an alternative to total backup, but as a procedure in parallel. It’s great for your peace of mind, for there will never be the question if your data are there and accessible to you.

    • And for the record, not only do I endorse this, but I do this. Except rather than external hard disks I use cloud services like DropBox. This way my current work is always quickly accessible regardless of where I am, and backed up off-site.

  5. And check the dates on the backed up files! I just lost 6 weeks of CRM data because CrashPlan Pro tells me a 16 bit app remained open for 6 months, with exclusive rights to the underlying database file, so even though I included that app in the master back-up AND its own back-up set, and BOTH ran DAILY for 6 months, the date on the database file is still December, 2013. The only reason it wasn’t WORSE was because its on a virtual machine, and I took a snapshot on April 14th or so. So all our work done after that day is GONE.

  6. It can be a nuisance, but it’s a good idea to open backed-up files to be sure they are not corrupted. Rather than open all the files, opening a few files might suffice, if you’re willing to play the statistics.

    One of my USB disks malfunctioned, and some of its files became corrupted. I backed up corrupted files for approximately 3 months. (16 null bytes appeared at the beginning of random files. E.g., some PDF files began with “^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@%PDF-1.4”, instead of “%PDF-1.4”. Ah, the perfidy of inanimate objects!)

  7. I agree with Leo’s comments on the process of verifying an image if one is concerned. Personally, I trust Macrium and Acronis to a fairly high degree and don’t worry that the backup may be corrupt. Both backup tools have a “Verify backup” option that does said verification after the backup is complete. The Macrium details can be found here: I definitely do an initial test that I can boot from my restore media and find/see my backups, but after that am confident that the backups completed properly by using the Verify option. Definitely takes a while to do the verification, but it’s running at night or while I’m at work and provides peace of mind.

    • I use Norton Ghost V15 which also has the Verification option. For a 40gb backup image, this verification only takes about 2-3 mins more than without it so I always use it. The whole process takes about 20 minutes. I also never check to see if a image works when I have verified it, and maybe I am lucky, but in 12 years of using Ghost, I not had any mishaps except for the very first image I tried to restore that I did not verify. Since that initial mishap, I recon I restored about 7-8 times over the years.

  8. Recently I wanted to restore my system from an image backup (Macrium) but my rescue disk could not find the internal drive on which it was saved. I had to use repair install of Windows to continue. It would be nice however if the rescue disk could find it. Do you have a suggestion for this?

    • Well, that was kind of the point of the article – to test for that situation before you need it. For the record, storing a backup on an internal disk is not recommended. I recommend instead an external drive.

  9. 1. Please indicate the procedure to test the rescue media. Do I have to go into BIOS to alter the boot order priority?
    If and when I see the drive containing my backup, do I then simply cancel the action? (I have already verified that the actual backup is successful.)
    2. I have Product Recovery Disks which I bought when I purchased my Toshiba computer. If I use these and get the factory setup in what way can I then use the Macrium Backup to complete the setting up?
    Incidentally, Macrium Reflect is so easy when you follow instructions. Thank you for your help.

    • 1. Testing the rescue media is exactly as you describe: boot from it, make sure that it can “see” your backup drive, and perhaps even take a few steps into the restore procedure without actually initiating a restore.

      2. The simple answer is that you cannot. They are two different things. A product recovery disk probably (there’s no standard) resets your machine to factory settings – i.e. Windows as of the day you got the machine. Macrium resets it to the state as of the last image backup. At best you could use the Macrium Backup to restore individual files after the machine has been reset by the product recovery disks. My preference is that the Product Recovery Disks never need to be used, because you can always restore to a Macrium backup image.

  10. Thanks for the marvellously prompt reply.
    I did think that individual files could be restored. However, your explanation makes it clear (and I agree completely) that going the Macrium way is the sensible path to take.
    Good luck with your highly-valued contributions to bringing matters computer within the range of young and old.

  11. More great information, Leo, thanks.

    Just a tiny warning for backup program newbies like me…when you said–

    “1. Testing the rescue media is exactly as you describe: boot from it, make sure that it can “see” your backup drive, and perhaps even take a few steps into the restore procedure without actually initiating a restore.”

    I did this very thing on my own after I made my first backup, intending to stop ‘just before’ it actually started the restore process, but I when I clicked expecting another window with more instructions, instead the restore took off running! I guess the restore process really is that easy! lol After minor heart failure I decided the best thing to do was not to try to cancel it but just cross my fingers. It worked! whew :) (I also always let the program do the checks after backup.)

  12. I’m a little late to this party, but maybe this will be of use. I use AOMEI Backupper Standard Edition (free) with full image and incremental backups. It has a ‘check image’ option which I always use. One morning my computer refused to boot, and after hours of trying to solve the problem by other means, I did a full restore which worked perfectly. It took a while, but my computer was back to normal, and whatever the problem was it has not bothered me again. (This was about a year ago.)

    My only complaint about AOMEI Backupper is that there are so many options it makes the learning curve pretty steep. But if you follow Leo’s general recommendations for backing up, it’s pretty easy to get up to speed.

    • I have to add — be sure to select AOMEI’s ‘local download’ button. C|Net routinely bundles 3rd party crapware and PUPs these days.

    • I’ve just hit a problem with AOMEI backupper and their tech people say “Backupper doesn’t support drives with 4096 bytes per sector” (quote is copied from their email). Note that the backup verified on AOMEI, but apparently it won’t actually work – on the default bytes/sector setting for an NTFS drive.
      Wish I’d known this before
      a) shelling out £44 for the Pro version so I could use their ‘clone’ feature, and
      b) using this program for over 5 months as my only backup strategy.
      I cannot recommend AOMEI and will now be using Macrium as Easeus can’t handle dynamic disks.
      It’s mildly surprising that so many of the well-known backup programs are , in fact, not up to the task. But only mildly – this is, after all, computing.

      • Not all apps do support dynamic disks, so check before buying! Outta curiosity, why did you create a dynamic disk? Basic is usually a better option….

  13. Leo describes a great way to check (verify) your image backup(s) up to the point of actually restoring from an image. Let me point out that you’re not only testing your image as much as can be tested without actually doing a restore, you’re ensuring that you understand the procedure for doing a restore, and that you have a functional restore tool (emergency rescue boot CD) that will allow you to get to your external disc that holds your images(s) should the need arise. Here are two additional things I do to enhance the recovery process that I use:

    First, I use a second tool for DATA backup and recovery, and the tool that I choose to use (FreeFileSync) is not only free, but it saves the backed up files in their native format, and creates a log of its backup results that I can check after doing a data backup. I find that both of those capabilities are important to the data backup process, especially the ability to copy data files in their native formats. That way, I can open some of the backed up data files using the tools that I created the original files in, and ensure that the data backup process did not “hiccup” and save my data files in an unusable or unreadable format. Let’s face it, it’s a major pain to do a new set up (OS and program files) from scratch, but backup and restoration of your data, and the ability to check the results of the backup, and restore data files and possibly even move data files from the backup to another computer for immediate use is what’s REALLY important!

    Second, the simplest way to fully test an backup image is to really restore it, start to finish. No, not by restoring the image to the disc that you backed up, but by having a new, blank hard disc on hand of equal or greater size on hand, removing the original (as if it had gone bad), and then installing the new hard disc, restoring to it, and then booting from it. Yes, that takes a little bit of money, some effort and a little bit of time, but isn’t it worth those things to know that your image backup process REALLY works? For myself, I’ve found that it IS worth the effort and money, and I recommend it in general. Hard disc storage space is really cheap these days, you can get by with buying only one extra hard disc for testing and verification purposes even if you have multiple computers, and the process even works for laptops and the newer two-in-one’s that don’t have a DVD/CD drive built-in (in that case, you also have to get an external DVD reader that plugs into a USB port so you can boot the emergency recovery boot CD from it). Added benefit to this method – if your primary hard disc really fails, you will likely have a recovered image already on your extra hard disc, so you can simply plug it in, do a data recovery (if necessary) to get the most current data back, and away you go! I mention this as a counter to Murphy’s law – your hard disc is always going to fail when the local retail stores are closed and just at the exact time that you must have your computer working, so KNOWING that your backups are reliable and having on in hand that you can immediately use can be, in many cases, worth its weight in gold!

    • Testing the image backup by buying a new drive and replacing the old drive in my notebook is not an option.
      On my previous HP notebook replacing the hard drive was simple, just remove a couple of screws and slide the hard drive out. Then sliding the new drive in and putting back the screws. Simple.
      With my current Dell notebook the process to replace the hard drive entails taking the whole notebook apart. Not something I really want to do myself.

      • Definitely don’t try it yourself. It’s really hard to get back together, tons of little pins that can get broken. I wonder why they started making the hard drives so hard to take out.

          • Try opening up a Surface or Apple product: you’ll have nightmares for weeks after. They even use proprietary screws that require a special tool in some devices!

          • When I upgraded my MacBook Pro’s SSD I ended up buying a kit that included not only the new drive, but the screwdrivers necessary to get at it. At least it was available from a third party.

  14. In addition to testing their backups, it’s also important for people to understand how their backup system actually works – or else things can go horribly wrong. For example, somebody I know used both the cloud and an external hard drive for backups. So he had three copies of his data – a copy on his PC, a copy on his external hard drive and a copy in the cloud- what could possibly go wrong? What went wrong was that his computer’s hard drive and his external started to fill up so decided to delete the data from both and start with a fresh set of backups. He thought it would be okay to do this as he had a copy of his data in the cloud and so didn’t need the local copies. Makes sense, right? What he didn’t realize, however, was that the cloud service was simply syncing with his computer – meaning that once he’d deleted the data from his PC, it was automatically deleted from the cloud too. Oops.

    • Hopefully, his cloud service keeps deleted files for 30 days. Dropbox does this, so if you use the paid version, you’d have 1 TB storage and you can keep all of your user files there. That’s how I do it. But I agree. Never let it get to that state. Always keep at least 1, better 2 full backups, and don’t trust a cloud server as the only keeper of your data. As Leo says, “If it’s only in one place, it’s not backed up.” In other words never have your data in only one place. As the famous lawgiver Murphy said, “If any thing can go wrong, it will.” That was the first law of engineering we learned on our first day of Intro to Engineering.

      • “Hopefully, his cloud service keeps deleted files for 30 days.” – Yeah it did but, sadly, he didn’t realize what had happened until the 30 days had elapsed. Something else that people often do not realize is that, when it comes to solutions like Carbonite that support both cloud and local backup, disconnecting the local device – maybe because it’s failed – may have the same effect as deleting files and start the 30-day counter.

        “If you have a Carbonite product that supports external hard drives, unplugging the external hard drive would be considered the same as deleting the files from your computer and the 30 day counter would start.”

        Again, this is something that can easily lead to an oh-no-where-the-****-have-all-my-files-gone? scenario.

  15. @Ray,
    OOOH!, that’s terrible!
    I have done similar things by not knowing it all about computer and their programs.

    Thank You, Ray and Leo for letting me learn this important tip.

  16. I am responsible for computer operations at my daughters law firm. The most important files are of course the client files. These files are backed up nightly to an online backup service. In addition an image is created on a local secondary hard drive. Among these files is a text file named “Testbackup.txt” that is created daily by a VBScript. Each night the file is modified to record the current date in the single line of text. I periodically check this file and match that date against the backup log date. if they don’t match I know I have a problem.

  17. Regarding the article’s method #2 (Extract files) for testing a disk image backup, I did this a couple of times with Macrium Reflect. Actually, they weren’t a test. I was trying to restore deleted folders in Windows XP I thought I no longer needed. Each time, I ran into the same problem. While in the administrator-capable user account, I browsed toward the desired folder in the disk image (G:\Documents and Settings\User Name\Desktop\folder). When I got to the User Name part, I wasn’t allowed to open it because Windows said: “You don’t currently have permission to access this folder.” What?!

    I don’t remember exactly how I got around this to access the desired folder. Later, I discovered Leo has an article that deals with this problem. Anyway, I just wanted to mention this to alert other readers to this potential issue. Because when you are trying to recover a lost file or folder from a disk image, you are probably in a mild state of panic already. And an error message dealing with permission is the last thing you want to see.

    Leo, I do have a couple of questions:
    1) Does this permission issue have anything to do with the fact that the disk image is saved on an “external” hard drive?
    2) Any idea as to what causes this particular permission issue?
    3) Is there anything users can do ahead of time to try to avoid this issue?


  18. Here’s what I did. My main worry, besides whether or not the image was any good, was would I be able to actually do a restore, as I had only recently tried Reflect. Well, coincidentally, I had an old Dell laptop that had seen better days. It was on my discard pile. So, before removing its HD, I tried a few things: including doing a BU/Restore. It worked so perfectly. My confidence went from 10% to 95%. Years later, I did have a s-ware crash and eventually I did have to restore from B/U. No problem. So…good use for old computer!


  19. I recently had to buy a new laptop as the old one (a reburbished Lenovo T430 running Win 7 Pro) was shewing signs of wear.

    Because I don’t like the look and feel of Win 10, I installed a Win 7 Pro lookalike. However, following my normal routine, I started a backup of the new disk complete with System Image. It went to 97% complete and stuck there for two days. I eventually deleted the saved partial system image and then backed up WITHOUT the image. That works and each day, at the scheduled time, it backs up.

    I seperately told backup to create a System Image and again, it stuck at 97%. I stopped the backup and have left it so.

    Is this a known problem?

  20. I back up 2 ways. once with an image backup program ( Macrium Reflect), and also I backup the files and folders with a synchronize program (Goodsync). That way if Macrium fails, I at least don’t loose anything but time it takes to reinstall Windows, and copy the files and folders back to c drive.

    • Good idea. I use OneDrive for that to keep them stored on Microsoft servers. Dropbox, Google Drive and others are just as good. I use OneDrive as it is included in my Office 365 subscription. In fact, I only subscribe to Office because of OneDrive. For the same price as Dropbox for business, I get more storage and MS Office. It it weren’t for OneDrive, I’d be using Libre Office. I also love MS Publisher for producing flyers and brochures but I can use Scribus for those.

  21. I agree with Ken Driver. In addition to doing regular backups using EaseUS ToDo Backup, I use FreeFileSync to back up (Mirror sync) all of my data files and configuration files for the different programs that I run. I store this on a different external HD than my EaseUS backups, and, additionally, I have it stored off site. My data files are the most important files to me; I can always put Windows and all other program files back if the Restore from EaseUS doesn’t work, but I cannot take any chances with my data files. I have FreeFileSync set to save, rather than delete, all earlier versions of my data files, as an additional precaution.

  22. I have two usb external drives I use for my backups. Recently, I put a spare drive in one of my external enclosures and restored one of my recent full backups to it. It worked perfectly and only took a few minutes to restore. I removed that drive from the enclosure and put it in my computer. It booted and ran just fine.

  23. Macrium works as well or better than others, but once when I needed to restore, I found all my backup files were corrupted. I had no idea. So it’s always best to have your files backed up on at least 2 different mediums, with 2 copy programs.


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