Technology Explained

What Is Data Recovery And How Does It Work?

Dann Albright 17-08-2014

We’ve all dealt with data loss, whether it was from a hard drive failure 4 Tools To Predict and Prevent Hard Drive Failure f there is one piece of equipment in your computer that you would predict to fail first, what would it be? Read More , data corruption What Is Data Corruption? How to Fix a Corrupted Hard Drive Data corruption can destroy the data on your HDD, so it's wise to keep backups. Too late? Find out how to repair your hard drive. Read More or accidentally deleting a file. If you’ve ever experienced a major loss of data, you’ve probably wondered about data recovery — how does it work? How effective is it? How much does it cost? We set out to find out.


Data Loss and Data Recovery

Data loss can take many forms — accidental deletion, hard drive failure, software bugs, data corruption, hacking, even a simple power failure can cause you to lose data. And, of course, there are more extreme cases, like when a hard drive is recovered from a plane crash; amazingly, some data recovery specialists can retrieve data from storage media that’s been almost completely destroyed.


If a piece of data used to be on your hard drive, solid-state drive, USB stick, RAID, or other storage media, you might be able to hire someone (or purchase some software) to perform data recovery. Data recovery is, simply, the salvaging and repair of data that has been lost.

Of course, data recovery won’t always be possible; sometimes a system can be too corrupted or damaged to get much of the data back. However, data-recovery technology has become extremely advanced; for example, Kroll Ontrack, an Australian data recovery company, was able to recover 99% of the data from a hard drive that was on the Challenger space craft when it disintegrated upon re-entry.

How Does Data Recovery Work?

The methods used to recover lost data depend on how the data was lost in the first place; let’s take a look at some of the most common forms here.


File Deletion

Interestingly, any file that’s deleted actually stays on your drive until it’s overwritten with another file. This means that if you act fast, you actually have a pretty good chance of getting the file back. In the case of file deletion, you can use file recovery software like TestDisk, which uses complex algorithms that look at pieces of information that’s left on the hard drive in order to guess where the file was physically stored. If it guesses correctly, you’ll get the file back. If not, you’re out of luck.


However, doing just about anything on your computer can result in the file being overwritten and likely lost forever. Even browsing the Internet can result in cookies or cache files being stored in that location, overwriting the information you’re hoping to retrieve. And installing file recovery software Recover Lost Data For Free With Pandora Recovery [Windows] Last night I inadvertently deleted 17GB of data with a mis-press of Shift+Del, causing a classic "oh sh*t!!" moment. I’d chosen to "permanently delete" the folder, skipping the Recycle Bin and instantly freeing up some... Read More can do the same thing. If the file hasn’t been overwritten, the chances of getting it back vary depending on the format of your file system.

For example, the Windows NTFS system retains file description information after the file has been deleted, making it relatively easy for file recovery software to find the file. Other systems, however, like UTF and FAT, destroy more information about the file when it’s deleted, making it more difficult for file-recovery algorithms to guess the location of the file on the disk.


File Corruption

If you’ve ever gotten one of the dreaded “corrupt hard drive” errors, you know how disheartening it can be. However, it’s still possible that data could be recovered. If you attach the hard drive to another computer, you might find that only the operating system has been corrupted, and that the rest of your data is fine—in this case, it’s just a matter of copying everything to another hard drive.

Another problem that could get you to this point is a corrupted partition table, which might be possible to repair using the correct software How to Fix a Corrupted Windows NTFS Filesystem With Ubuntu Read More . If you can successfully repair the table, it should be easy to get all of your files back. If not, you still might be able to recover enough information from the table to get your files back, though it depends greatly on the level of corruption.


Even if the files you’re trying to recover have been corrupted, there’s a chance that you’ll be able to get usable portions of them back by using recovery software Recover Accidentally Deleted Files From Any OS With PhotoRec [Windows, Mac, & Linux] In June I switched over from a combination of Windows and Linux to pretty much using OS X solely, and being largely familiar with Windows software (and painfully aware of the lack of many Linux... Read More ; as long as the software can find the file, it will try to recover it. While you might not be able to use what you get, there’s always a chance that you’ll get a portion of the file back, which could potentially save you a lot of time in trying to recreate it.


File System Format or Damage

Similar to deleting a file, formatting a file system From FAT To NTFS To ZFS: File Systems Demystified Different hard drives and operating systems may use different file systems. Here's what that means and what you need to know. Read More destroys information about the previous files and structure of the disk, but the amount of data that’s erased depends on the system format.

For example, formatting with FAT results in the destruction of a large amount of data and rewriting that section of the disk with zeroes, significantly reducing the likelihood that you’ll be able to recover your data How to Scan a Reformatted Hard Drive to Recover Files Read More . Some file systems, like NTFS, will have a higher likelihood of recovery if they’re overwritten with the same file system, while others actually have a smaller chance if they’re overwritten with the same system — writing XFS over FAT makes it more likely for the FAT files to be recovered.


In the case of file system damage, the number of files that can be recovered depends on the extent of the damage and what allocation information is still available to the recovery software. If enough information is present for the recovery software to repair the file system and accurately locate previous files, you should be able to recover quite a bit.


Physical Drive Damage

Recovering files that have been deleted or formatted is one thing — getting files off of a drive that’s been damaged How to Repair a Dead Hard Disk Drive to Recover Data If your hard disk drive has failed, this guide will help you with the hard disk drive's repair and data recovery. Read More is another. While it doesn’t take impressive technical skills to install and run recovery software, dealing with a heavily damaged drive is best left to the professionals, as it usually requires that the drive be taken apart.

Taking a drive apart without damaging it is very difficult — the professionals only open them up in clean rooms, which are highly controlled environments that are free of almost all environmental pollutants. Even a single speck of dust that lands on a hard drive plate can cause the read/write head to crash and multiply the drive’s problems. Static electricity can also damage the drive, so these rooms, these equipment used in them, and the clothing that technicians wear are all specially designed to minimize static.


When a hard drive fails because of physical damage, it can be related to a number of factors, such as a broken controller board or a crashed head. Occasionally these issues can be fixed by replacing the broken part, but in general, if there’s physical damage to the hard drive, you’re going to need some serious work done by the professionals.

If you get your drive to a data recovery specialist, they’ll take a number of steps, from rebuilding parts of the hard drive to creating a disk image and doing their best to repair the corrupted parts using sophisticated software. The cost of the rebuilding, proprietary imaging technologies, and maintenance of the clean rooms is what can drive the cost of professional data recovery upwards of several thousand dollars (though some providers are now able to offer more affordable rates).

Solid State Drive Data Recovery

Solid state drives How Do Solid-State Drives Work? In this article, you'll learn exactly what SSDs are, how SSDs actually work and operate, why SSDs are so useful, and the one major downside to SSDs. Read More are becoming more and more popular, especially with the rise of the ultrabook What Is An Ultrabook & Can It Succeed? [Technology Explained] Remember when the word laptop described virtually every mobile computer on the market? The choices were certainly easier back then (because there was simply less choice available), but today there’s a far wider variety including... Read More . Obviously, because they haven’t been around as long, recovering data from an SSD is more difficult than it is to recover from a traditional hard drive. However, a number of the same techniques can be used to recover data that’s been deleted or formatted.


However, recovering data from a physically damaged solid state drive can be very expensive, as the technology is still new. When my SSD crashed, the estimate for data recovery on it was about $3,500. A recent white paper estimated that this was average for SSD recovery if the recovery specialist had not received tools and specifications from the manufacturer; that cost was reduced to about $700 if the manufacturer provided support. Hopefully we’ll be seeing this cost come down in the near future.

Your Best Bet: Don’t Lose Your Data

Data recovery software and specialists can do a great job of getting your data back, but it’s risky, time-consuming, and expensive. The best measure you can take to prevent long-term data loss is the one we’ve been advocating for a long time: make lots of backups! Use a cloud backup provider Read This Before Choosing An Online Backup Provider Backing up your files is a no-brainer - at least it should be. Hardware failure, security breaches, natural disasters, thieving scumbags and clumsiness can all lead to heart-in-mouth moments when you realise that your precious... Read More , keep a backup hard drive in your home, and make sure you don’t get caught out by a power surge or an accidental formatting. And take steps to prevent file corruption What Is Data Corruption? How to Fix a Corrupted Hard Drive Data corruption can destroy the data on your HDD, so it's wise to keep backups. Too late? Find out how to repair your hard drive. Read More in the first place.

Have you ever used data recovery software or hired a specialist to recover lost data? Share your experiences below!

Image credits: Alchemist-hp via Wikimedia Commons, Kenny Louie via flickr, Ervins Strauhmanis via Flickr, stallio via Flickr, a binary code in multiple levels with one and zero via Shutterstock, NASA Goddard Space Flight Center via Flickr, Dr. Martin Von Nostrand via Flickr.

Related topics: Data Recovery, Hard Drive, Restore Data.

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  1. hozaifa elfiky
    November 22, 2018 at 9:59 am

    very good

  2. The Legacy
    May 11, 2018 at 10:27 pm

    Simple answer: RAID 1! Two hard drives, identical data, all the time. If one fails, the other is still there. Doesn't help with accidental deletion, but DOES help if one drive starts to physically fail.

  3. Jenna Bowser
    March 16, 2018 at 3:12 am

    I have experienced many times in data loss like all my family pictures on my SD Card was gone. It was really frustrating since I don't know how to recover it. I was begging my partner with tears asking him to recover my files. I don't know what best partition recovery software he used just after an hour my files were recovered. I was relieved and happy that my files were recovered that time.

  4. anna
    June 13, 2017 at 5:30 am

    Thanks article!
    uFlysoft supports almost all file formats for NTFS & FAT32 file systems. Therefore you can recover files not only on your Mac but also on USB Flash drives, external hard drives and other portable devices.

  5. Tai austin
    April 11, 2017 at 10:20 pm

    My videographer told me his hard drive crashed where he had recorded our kids baptism event. He said he send it to California to get it fixed it's been 9 months and he is still telling me the same thing. It's me and 6 other clients videos/photos were there does it take that long to get it fixed? Is he lying to me or does he not want to give me the bad news? Please help!

    • Dann Albright
      April 22, 2017 at 3:16 pm

      Hm, that's a tough question. As far as I'm aware, it doesn't usually take that long. However, if the service is really backed up, it's possible that they just haven't been able to get to his hard drive yet. You could ask him which company he sent it to and follow up with them; that's probably your best bet for getting a straight answer.

    • anna
      June 13, 2017 at 5:30 am

      uFlysoft supports almost all file formats for NTFS & FAT32 file systems. Therefore you can recover files not only on your Mac but also on USB Flash drives, external hard drives and other portable devices.

  6. Gabriel
    January 17, 2017 at 2:31 am

    Very informative articles, best way to prevent data loss is using automatic backups.

    • Dann Albright
      January 18, 2017 at 11:28 pm

      Yeah, there's really nothing better than having it all automated. But many people learn that the hard way.

  7. Alplaza
    May 2, 2016 at 4:23 am

    I wonder if the data recovery company can recover any data from a usb / hddthat is destroyed with magnet . Tried it on a old usb ( no sensitive or important data on it )

    • Dann Albright
      May 3, 2016 at 1:42 pm

      Hm, I'm not sure about that. You'd probably have to ask each individual company. My guess is that some would at least give it a shot, and that there would be a chance that you could get some data back.

  8. Anonymous
    April 14, 2016 at 3:37 am

    Hi Dann,

    I came across your website during a data recovery search. Recently I have lost some of my precious data from my Mac El Capitan Hard drive. I just want to know whether the software like Stellar Phoenix Mac Data Recovery, TestDisk etc. can take guarantee to recover the deleted data?
    System specifications: MacBook pro 10.11 with 3 GB of RAM and 500 GB of hard drive

    • Dann Albright
      May 3, 2016 at 1:41 pm

      As far as I'm aware, they don't usually offer a guarantee, but you'd have to check the providers' websites to make sure. Hope you've found a good solution!

      • douglas gordon
        May 9, 2016 at 2:59 am

        Thanks for your concern Dan!!!

        Stellar Phoenix Mac Data Recovery software worked for me and recovered my hard drive. Though in the beginning it took some time to scan the disk but through the halfway it started speeding up and recovered all my files like a champ.

  9. bonquesha
    March 11, 2016 at 10:25 pm

    Read the data recovery software review also

    • Dann Albright
      March 12, 2016 at 12:17 am

      You mean before you choose a specific piece of software?

  10. Anonymous
    December 30, 2015 at 7:32 am

    Time Machine would only help you in the future. Is your Mac set up with Time Machine? If so you should be able to get the deleted files that way. Click the Time Machine icon in the dock. Then go back to before you deleted the files, they are probably still available. f you don't have a Time Machine backup yet, then your best option would probably be uFlysoft Data Recovery for Mac

  11. Anonymous
    September 18, 2015 at 7:38 pm

    I had to reinstall my (Vista) OS from the factory partition and naturally lost my data. RECUVA was useless as were a few other freebies that I tried. So I'm ready to take the next step and seek a personal data recovery utility that is reasonably priced. Any luck stories that you care to share?

    • Dann Albright
      September 19, 2015 at 3:40 pm

      Fortunately, I've never had to use data recovery myself (that's not totally true; I was hoping to once, but couldn't afford it), so hopefully someone with more experience can chime in!

  12. Anonymous
    August 18, 2015 at 6:21 am

    Hi, my Dell external hard disk (1tb) is not readable in any laptop or PC, i have an important memory in it so what is the best option to recover my data or to resolve it, please anybody can help? cheers

    • Dann Albright
      August 20, 2015 at 10:36 pm

      Did you read the article above? It lists a number of different ways to go about getting your data recovered. Also, you might consider posting the details of your HDD and your computer in our Answers section, where people who know more about the specific devices you're using might be able to address your issue.

  13. Anna
    December 1, 2014 at 1:56 pm

    I have my HDD failure and have no back up of the data.Can someone Suggest a good online free data recovery tool or a data recovery company in India?

    • Dann Albright
      December 2, 2014 at 8:29 pm

      Anna, I'd recommend posting this in the Answers section (just click on Answers at the top of the page)—you're likely to get a lot more answers there. There are probably a lot of people out there who can help out!

  14. Michael Hudson
    August 27, 2014 at 4:51 am

    Challenger didn't disintegrate on re-entry....Columbia did...Challenger exploded on take-off and never left the lower atmosphere....Maybe they did recover data from the Columbia shuttle... I dont think the same kind of modern data storage technology was in use in 1986 when the disaster occurred, and the systems onboard Challenger probably didnt rely as heavily on computer data as Columbia...Nevertheless, I just wanted to point out a factual discrepancy in your article...good information though

    • Dann A
      August 27, 2014 at 2:47 pm

      Oops. You're right. The drive was from Columbia. Thanks for pointing that out. :-)

  15. Giorgo
    August 19, 2014 at 4:42 pm

    I've tried Northwind Data Recovery, they're WD partners and seem to know what they're doing. Got all my data back at reasonable fee. Found 'em at

    • Dann A
      August 26, 2014 at 1:15 pm

      Thanks for the tip, Giorgio!

  16. Jonathan
    August 18, 2014 at 3:56 pm

    Agreed Adrian, I trust cloud service providers as much as a random person on the street - not a single bit. I back up all my important data on a couple of external drives. For data recovery - fairly easy when the files have been deleted - plenty of software for it. From physical damage? Hate to say it but might as well continue destroying the drive to make sure no one else gets their hand on it.

    • Dann A
      August 26, 2014 at 1:12 pm

      Yeah, software-based data recovery is a cinch. Physical damage recovery is highly technical, though. However, I think finishing off the destruction might be a bit drastic; I'm sure there are companies out there who would be happy to pay the $10,000+ for a team of RAID specialists to get their data back instead of trying to recreate it!

  17. Adrian
    August 17, 2014 at 11:14 pm

    Yes data recovery is painstaking and there are no guarantees.

    I've got several local backups but I'm not sure I'll ever trust a cloud backup. I remember losing all access to an e-mail account after the provider deleted it claiming that I had violated its terms of service. What's fearful is that the email provider refused to grant me access to my data...saying they had the right to do so and would only grant access to information if petitioned by the court.

    Luckily I had by local backup so I didn't lose anything. But if an online email provider can block access to one's data what guarantee does one have that a cloud storage provider wouldn't do the same? Then there's the whole issue of privacy and who has access to your info when it's in the cloud...scary.

    • Dann A
      August 26, 2014 at 1:06 pm

      I understand your concern; having all of your data just out there somewhere isn't a real comforting idea. However, cloud backups are extremely useful, so it's a bit of a risk that's probably worth it. I'm a big fan of having local and remote backups to make sure that you don't have to deal with data recovery. The more redundant backups you have, the better!

    • John P
      August 28, 2014 at 6:44 am

      Several types of data corrupted from storage drive like Hard disk, digital media like SD card or Pen drive. But your data logically corrupted or physically corrupted
      If your data physically corrupted then you want data recovery services but your data logically corrupted then you recover data through give tip at here