Beginners Guides: Hard Drive Data Recovery
Killed a hard drive without backing up? This guide helps you recover the data - Version 1.0.1
If you've been using computers for a decent amount of time there is a good chance someone has told you that data stored on a hard drive is not exactly safe. I'm here to assure you that this is indeed true.
Never mind the fact that unlike tapes or CDs or other methods of storage, hard drives are mechanical, active devices and are thus subject to comparatively rapid breakdown.
No, the real threat to hard drives are the people that use them, by which I mean you and me. Hard drives, being the dynamic storage devices that they are, are extremely easy to erase in any number of amusing and simple to achieve ways... as are USB hard drives and flash memory cards (recovery tips for that media is detailed here).
Working as a computer tech during the glory days ofWindows 98, you get rather used to using FDISK and other hard drive utilities to prepare and repair customer's drives, which leads to a certain over confidence. That attitude can lead straight to disaster, sort of like giving a 12 year old boy the keys to an ATV.
Picture this if you will; there I was, two or three sentences and a screen shot away from finishing a 5000+ word article on computer upgrades. All I had to do was fire up FDISK on a dual boot Windows98/XP Pro system and grab a few screen shots. I figured I'd write a little blurb on how to partition a drive, making sure to tell the readers not to mess with FDISK if they were not sure what they were doing…
Yes, there's going to be some irony here.
So anyway, I wanted to get some more screen shots of the actual partitioning screen, but I did not have a blank hard drive handy. I figured I could use my NTFS formatted XP drive (which FDISK perceived as a blank drive) to start the "process," grab the screen shots and then cancel the partitioning.
No problem. Except for one little thing…
I had forgotten thatFDISK, in the process of checking the disk before it prompts you for the size of the partition, writes information to certain areas of the hard drive. This data writes over whatever might have been there before. Meanwhile, there I was, watching the '%complete' counter and wondering why a little red warning flag kept going off in my brain? I restarted WinXP and waited for it to boot, and waited... and waited... Oops. Primary Partition Gone?
Thehard drive that suffered the data loss was a 17Gb drive with two 5Gb XP NTFS partitions (Home and Professional) and 6Gb of unused space. Both XP partition were unbootable after the incident.
After transferring the drive to aWindows 2000 computer so I could use disk manager, (to load disk manager on XP or 2000, right click 'my computer' select 'manage' then 'disk manager') this is what I saw.
The Primary partition where my 5000+ word article was saved, is seen as unformatted and cannot be read by the OS. The second XP partition could not be booted, but was seen as formatted and I could transfer files easily from it using explorer. Unfortunately, all the data I needed was on the first partition.
What to do? Well there are a few tricks you can use to get data back from the brink of an abyss like the one I've created for myself here. First though, we should understand exactly what afile system is, and how it controls access to your data on a computer.
An overview of file systems
A file system is a method anoperating system uses to arrange data and free space on a hard drive or other storage device so it can be written to and read from. File systems create partitions which are areas of free space than can be addressed by the file system and seen as a logical drives (C: D: etc.) to be written to and read from.
The two file systems used by the various Windows operating systems are NTFS (NT File System) and FAT (File Allocation Table). FAT is an earlier file system, used first in DOS as FAT-16, then later in Windows 9x/ME as FAT-32.
The only major difference between FAT-16 and -32 is in the amount of data they can address. FAT-16 can only use up to 2GB of space on each logical drive, and FAT-32 has no such limitation. LaterMicrosoft operating systems like Windows 2000 and XP are fully compatible with FAT, even if it is not the default method they use to store files.
NTFS is used in Windows NT, 2000 and XP and provides a more secure and efficient method of file storage. In addition to allowing security to be implemented on individual files, NTFS also storesbackup copies of essential disk information to aid in recovering from disaster.
Both file systems use the Master Boot Record (MBR) and partition table, found in the first sector of each hard drive or storage device. The MBR and partition table determine which partition(s) on the disk are bootable, and locate and pass control to that partition to boot the operating system.
If the MBR or partition table are damaged, the drive will become unbootable, and may appear to be blank if the partition information has been erased.NTFS partitions
The first sector of NTFS partitions is reserved for the partition boot sector. This contains the information that allows the OS to read the partition. Without it, the partition cannot be accessed.
By its nature, NTFS keeps a backup copy of the boot sector on the last sector of the partition which can allow recovery programs to restore it. The FAT equivalent of this is also called the boot sector, and resides on the first sector of the partition. The difference is that FAT does not keep a backup copy of this information, making recovery much more difficult...
The first file stored on an NTFS partition is the Master File Table(MFT) which is essentially a listing of the names, properties and locations of all the other files in the partition. This is referenced by theoperating system to access individual files.
NTFS stores a backup copy of this file. Data restoration software will attempt to access or restore a copy of the MFT in order to access files on the partition.
FAT partitions use something similar, called predictably enough the File Allocation Table (FAT). The FAT is also backed up on the disk, and can be restored bysoftware. The major disadvantage of the FAT as compared to the MFT is that it needs to be located on a specific area of the partition to function, so if that area of the disk is damaged, recovery can be difficult.
When a file is deleted (removed from the recycle bin within Windows), bothfile systems simply mark the file as deleted. The data is not actually removed from the drive, but rather the space it takes up on the disk is now considered to be free. Consequently, if you delete a file accidentally, you have an excellent chance of being able to restore it provided you do not write more information to the disk.
In my situation, I had two NTFS partitions on the effected disk. When I ranFDISK, it wrote garbage information over certain areas of this disk, including areas of both partitions. As a result, the first partition (the one with my article on it) had lost its partition boot sector, meaning it could not be accessed normally by an operating system. The second partition had merely had crucial system files overwritten, and was unbootable, but still fully accessible once I transferred the disk to another computer.
Thankfully there is a way to fix all of this, and get the data back!
First, a small disclaimer: All the processes described from here on are strictly for resolving software issues with your data, like accidentally deleting partitions or files. If yourhard drive has a physical problem, if it is making strange noises, shaking, rattling or smoking, nothing here will apply. Turn your computer off, unplug the drive and call a data recovery service if your files are vital.
Attempting to self-service your hard drive it may only make things worse.Steps to recovery
The number one rule to follow when you have lost data is to not write anything more to the affectedhard drive! This rule stands true for any situation...
If you have deleted a partition by accident, do not create another partition, just leave it blank.
If you have deleted files from the recycling bin that you realize you need, do not (if possible) save anything to the drive. The reason for this is that hard drives do not actually erase anything, not data or partitions. When you erase a file from theoperating system, it is just marked on the drive as having been deleted. When the system needs to store more data on the drive, it will consider files on the drive marked 'deleted' as being empty space, and cheerfully copy over them. If that happens then you're in big trouble.
The same rule applies twice over for partitions; since partition information just presents the operating system with a way of addressing the space available on the drive. If you wipe out a partition everything from it will seem to be gone.
So if there is no partition information, no data can be read by the operating system. This does not mean that your data it is not there however, only that you can't see it.Data-recovery programs have no such handicap.
What I had done in my zeal was to allow FDISK to test the integrity of the drive, which it does by writing a pattern of data to certain areas. Of course, in my case, many of these areas contained partition information and/or critical system files. The result was one missing partition, due to a destroyed boot sector, and one unbootable (but still readable) XP installation. The good news? I got it (almost) all back.
The first, and best thing to do in a data-loss situation is to make sure no more data is written to the drive. Obviously, if you have just the one partition and it's fried, you can't boot normally to the operating system. The best option in this situation is to transfer the drive to another computer, preferably one using the samefile-system as your damaged partition (i.e. the same operating system, or a newer version). See the PCstats Guides sectionfor information on how to move your hard drive to another computer.
Transferring the HDD to another computer has the dual benefit of preventing the drive from being written to accidentally, and potentially allowing you to retrieve information from the disk just by using Windows Explorer to look through file structures.
If you have damaged or erased essential operating system files, but the partition information is still intact Windows will not boot. The HDD can still be read from a different operating system which is one way out of the doom and gloom.
This was the case with one of the two XP partitions on the disk I mangled, as I was able to fully access it after moving the hard disk physically to another computer.File recovery programs
If you do not have the means to physically transfer the hard disk, resist the temptation to re-install your OS. There are several software tools available which will enable you to boot your computer with an alternativeoperating system and then help you try to recover the files.
The simplest way to gain access to the files on yourhard drive with a toasted OS is boot your computer with a DOS boot disk and then use a DOS compatible file recovery program such as Testdisk, detailed below.
Note that if you have a single hard drive with a single partition that is no longer bootable, file recovery becomes instantly more difficult. Most recovery programs will need a place to copy recovered data, and if you are using the same drive which has the lost data on it you have no guarantee that you will not be destroying more data than you save. It's a far better idea to either install a new hard drive onto the current system and put a new OS on that, or find another computer to transfer the lost hard drive to.
That said, there are several programs such as 'Winternals Disk Commander' and 'ERD Commander', that will boot your system straight into DOS or an alternate OS, then perform file recovery. None of these programs are free however.
If you have installed your hard drive into another computer, or if you have put a new drive with a separate OS into your current machine in order to boot, you now have a couple of advantages: Firstly, You can attempt to access your lost data normally through Windows File Explorer. This will not work if the partition information has been changed, since the OS will not 'see' the logical drives.
Secondly, You can safely play with recovering your files, since you now have a completely separate hard drive on which to put recovered data without compromising the source (lost) drive.Freeware Recovery Programs
If there is one problem with the area of, it's that companies know that a functional recovery program is something that people will pay good money for. Hence freeware and non-crippled shareware programs are thin on the ground.
There are a few options available though, so on with the list. Please read these through carefully before deciding the next step you will take.FINDNTFS Freeware
FINDNTFS (URL: http://inet.uni2.dk/~svolaf/utilities.htm ) is a rather effective free program to locate and recover NTFS (NT File System, The default method of storing files on Windows 2k/XP) files. It is available in several versions, including one that will run from a DOS boot, and thus can be used when the Windows OS is not bootable.
FINDNTFS is capable of several things besides finding and copying lost files, but that is what we will focus on for now.
To use FINDNTFS, boot your system into DOS using aboot disk with the findntfs.exe file on it. To obtain a list of NTFS files and directories on the drive you are attempting to recover from, type 'FINDNTFS # 1 1 1 c:\recoverlog.txt files' at the command prompt. The "#" should be replaced with the number of the hard drive you are reading from. If you have only one drive, it will be '1', if there is more than one drive in the system the physical hard drive with the 'c:' logical drive on it will be '1'.
This command tells The FINDNTFS program to search the entire specified disk for NTFS files, and output the file list to a text file on the C: drive.
Note that you can save the text file under any name on any drive, as long as it has the '.txt' extension. Do not save the log file onto a drive you are trying to recover data from however.
Once saved to another drive you can view the log file, which should look something like this.
If everything went well, you should have a reassuring, if somewhat jumbled list of the available NTFS files on the drive you selected. Search the document for the filenames that are most essential, and then scroll up until you see the directory that they are in.
You will need to do this, since the directory order that FINDNTFS sees will not necessarily be the same as you had before the data was lost. Note down the number of the directory before proceeding on with the next step.NTFS reader for DOS
Tousing FINDNTFS, you need to use the 'copy' command. A limitation of the program is that it will only save recovered files into the directory where the FINDNTFS executable is located, so make sure you have enough space available to hold your restored files.
Type 'FINDNTFS # (replace "#" with thr drive you are recovering from, as before) 1 1 1 copy #'. This is the directory number holding the files you wish to restore. You may enter up to 10 directory numbers. If you do not enter a number, the program will attempt to restore and copy all NTFS files on the selected disk.
FINDNTFS will copy the selected directories and files to the directory containing the FINDNTFS.exe file. Check the recovered files to make sure they are not corrupted.
Sadly, FINDNTFS has one major limitation. It cannot copy NTFS files onto DOS readable (FAT) partitions, and therefore is not able to recover files without an NTFS supportingoperating system running (Windows NT/2K/XP). Thus it is not possible to recover files directly with this program using a DOS boot disk.
NTFS reader for DOS Freeware
NTFS reader for DOS (URL: http://www.ntfs.com/products.htm) can copy NTFS files onto DOS (FAT) partitions. In fact, that is the only thing it does, but what a useful thing... If your NTFS disk is unbootable, you can put this program on a floppy and copy files from the disk onto the floppy. Very good for rescuing essential documents that need to be completed.
The limitation of this program is that it cannot read from partitions that have damaged boot sectors, or from drives with damaged partition tables, as it needs to be able to see the NTFS partition before it copies data from it. The company that made this software, 'Active@Data Recovery Service' (www.ntfs.com), offers a commercial version, 'Active@ Partition Recovery', which adds the ability to search the drive for lost partitions as well as copy data, making it a complete recovery tool.
Note that NTFS reader will also work under Windows 9x/ME but not on 2K or XP, due to restrictions these Operating systems place on accessing drives directly.TESTDISK, The Holy Grail
Test disk (URL: http://www.cgsecurity.org/testdisk.html ) is a DOS only tool (also available for Linux) that can be used to locate and recover lost partitions (FAT and NTFS) by repairing the partition table or replacing partition boot sectors with thebackup copies.
Using this program, I was able to make my first partition (the one with the articles) accessible by restoring the backup partition boot sector, enabling theoperating system on the computer to 'see' the partition again. I was happy. Testdisk is not overly difficult to use, but it does require a bit of attention. First, please read the documentation (located in the 'doc' directory) for an overview.
Upon starting Testdisk, you get a screen listing your available physical drives at the top.
Highlight the drive you wish to recover and select the 'analyze' option.
It will show the current partition structure and upon hitting 'enter,' will start searching the drive to see whether the actual partitions match. Make a note of this. If you have erased your partition table, nothing will be shown here.Testdisk Backs up Lost Data
Once this search is complete, hit enter again. It's a good idea to run the 'search!' option to do a more comprehensive search of the drive.
If you initially had no partitions shown, because of a damaged or wiped partition table, Testdisk will now hopefully have rediscovered the partitions.
Verify the information and select 'write' to save the new information onto the disk. If removing your partitions was the only damage you did, you should now be up and running again.
If you damaged the partitionboot sector on your partition, (as I did) you should select the 'advanced' option, then 'boot.'
Testdisk will compare the boot sector to the backup boot sector. If they are identical, it can do nothing more, but if they are different it will ask you if you wish to overwrite the boot sector with the information from the backup.
This operation made my 'lost' partition with the articles on it accessible again. Testdisk is an extremely useful tool for partition recovery. Though it lacks agraphical interface and can only be run from DOS, it is capable of restoring lost information in minutes. Commercial Data Recovery Utilities deleted files that are no longer in the Recycle Bin. Commercial Data Recovery Utilities
There are many excellent commercial recovery packages out there. The majority of these are designed to access the disk through anoperating system, in which case you will need to have your affected drive transferred to another computer, or at least have a separate drive with a new OS on your original system.
These programs generally use the 'virtual recovery technique, which involves creating an 'image' of the disk to be restored in memory and then transferring files from that image to an alternate hard disk. Two good examples of this type of program are 'Active File Recovery' and R-TT.com's R-Studio.
I did not comprehensively test any of the listed programs, but when I first lost my data, I used several demo and preview versions of the following software to ascertain that my data was actually still there. One standout was R-Studio, whose demo version allows the recovery of files up to 64K in size, allowing me to move my articles safely off the drive before commencing the recovery in earnest. Highly recommended.
From previous work experience, I can also recommend 'Winternals Disk Commander', though they do not provide a preview of thesoftware. Following is a partial list of commercially available partition/file recovery and undeletion software we suggest you check out if the freeware we have already mentioned hasn't done the trick.
If you have any comments or questions, please post them in the PCSTATS Forums. Find out about this and many other reviews by joining the Weekly PCstats.com Newsletter today! Catch all of PCSTATS latest hardware reviews right here.
Copyright © 2002