Ddrescue For Windows 7
Ddrescue - GNU Project - Free Software Foundation (FSF) Ddrescue - Data recovery tool IntroductionGNU ddrescue is a data recovery tool. It copies data from one file orblock device (hard disc, cdrom, etc) to another, trying to rescue thegood parts first in case of read errors.Ddrescuelog is a tool that manipulates ddrescue mapfiles, shows mapfilecontents, converts mapfiles to/from other formats, compares mapfiles,tests rescue status, and can delete a mapfile if the rescue is done.Ddrescuelog operations can be restricted to one or several parts of themapfile if the domain setting options are used.The basic operation of ddrescue is fully automatic. That is, you don'thave to wait for an error, stop the program, restart it from a newposition, etc.If you use the mapfile feature of ddrescue, the data are rescued veryefficiently, (only the needed blocks are read). Also you can interruptthe rescue at any time and resume it later at the same point. Themapfile is an essential part of ddrescue's effectiveness. Use it unlessyou know what you are doing.Ddrescue does not write zeros to the output when it finds bad sectors inthe input, and does not truncate the output file if not asked to. So,every time you run it on the same output file, it tries to fill in thegaps without wiping out the data already rescued.Automatic merging of backups: If you have two or more damaged copies ofa file, cdrom, etc, and run ddrescue on all of them, one at a time, withthe same output file, you will probably obtain a complete and error-freefile.
This is so because the probability of having the same area damagedin all copies is low (if the errors are randomly located). Using themapfile, only the needed blocks are read from the second and successivecopies.Ddrescue recommendsfor compression of backups because the lzip format is designed forlong-term archiving and provides data recovery capabilities whichnicely complement those of ddrescue. (Ddrescue fills unreadable sectorswith data from other copies, while lziprecover corrects corrupt sectorswith data from other copies). If the cause of file corruption is damagedmedia, the combination ddrescue +is the best option for recovering data from multiple damaged copies.Recordable CD and DVD media keep their data only for a finite time(typically for some years). After that time, data loss develops slowlywith read errors growing from the outer media region towards the inside.Just make two (or more) copies of every important CD-ROM/DVD you burn sothat you can later recover them with ddrescue.The mapfile is periodically saved to disc.
OK, it seems that a guide for using ddrescue might be of some benefit to many members who may be shy of the linux terminal. So, I've decided to document some real-world examples from in the shop. I plan on doing this in 3 parts to cover the most common scenarios.Part 1: Creating an image from a failing diskPart 2: Restoring an image to a new disk & cloning directly to a new diskPart 3: Working with the image filesIn will be using Parted Magic as a platform for this guide.
I usually PXE boot (or boot from a live CD) the machine that I am working on to Parted Magic for this purpose. If you run linux on your test bench machine and prefer to attach the failing drives to it, this guide will give you the basics, but obviously the screenshots will be different. Part 1 – Creating an Image from a Failing DiskFirstly, a refresher on how unix/linux names block devices (hard drives, usb drives, cdroms, etc). These devices are represented as files within the /dev directory.
Hard drives are usually denoted with the “sd” prefix, followed by an incremental alphabetical designation, beginning with “a”. So, the first recognized device will be /dev/sda, the second will be /dev/sdb and so on.
Furthermore, the partitions on a particular drive are represented by incremental numbers. For instance, /dev/sda1 is the first partition on the first hardrive, /dev/sda2 the second partition on the first drive, and so on.For our purposes, this is relevant because we may want to image the complete drive (say /dev/sda), which includes everything (MBR, partition table, all partitions). Or, we may just need to image a single partition (say /dev/sda2). If you just need to recover files from a Windows partition, it is advisable to only image that particular partition (as opposed to the entire disk). If, on the other hand, you intend to rescue the whole drive, replace the failing drive, and re-image; then certainly image the whole drive so you get the MBR, etc.If you want to see a list of the block devices currently attached to your system, run this command. Code:# lsblk -o name,label,size,fstype,modelIn Parted magic, you will get something like this (from my guinea pig laptop)as you can see, there are two hard disks attached:1. /dev/sda, which contains two partitions: /dev/sda1 and /dev/sda2.
This is the Windows8 drive installed in the laptop.2. /dev/sdb, which is my attached USB drive and contains a single partition: /dev/sdb1At this point you will want to make note of the name of the drive or partition that you want to rescue, and the name of the drive where you want to store the image. 727 star trek ebooks (epub & mobi).
Be aware, that if you have multiple drives installed, it is possible that these designations can change after a reboot; so be sure to double check before you proceed.In this example, we are going to image the whole Windows8 drive in the laptop to an image file stored on the attached USB hard drive.The first thing to do is to open the “File Manager” from the Parted Magic desktop and browse (and/or create) the directory on your USB drive that you intend to store the image and the logfile on. In this example, I will be storing the image in the root directory of the USB drive.
Note: Do not mount/browse the drive you are trying to rescue. Make sure the drive you plan to store the image on has sufficient capacity.
If you are rescuing a 500gb drive, you must have at least 500gb free to store the image.Make sure you are located in the directory where you intend to store the image in File Manager and select “ File-Terminal”, and a new terminal window should open with the directory you have chosen as the working directory.The syntax for the command we are going to use is. D tells ddrescue to use direct disk access and ignore the kernel's cache-r3 tells ddrescue to retry bad sectors 3 times before giving up. Note: On a failing drive you may want to eliminate this option the first time so as to not waste time hammering on bad sectors and risking drive failure. You can always use the logfile to go back and retry the bad sectors after you get an image from the first sweep./dev/sda is the drive we are rescuing.the whole disk. Naturally, if you just wanted a specific partition, you would use something like /dev/sda1 instead.test.img is the name of the image filetest.logfile is the name of the logfile. Always use a logfile. This allows you to resume an interrupted image at the point you left off, or to retry bad sectors after an initial pass.
Without a logfile, you will have to start over again!Notice the appearance of the new files in the File Manager pane (test.img and test.logfile). This process will take a good while.
It's not uncommon for a large drive with lots of damage to take days to complete.More to come. Part 2a: Restoring an image to a new diskLet's assume now that our image from Part 1 is complete. If our intention is to replace a defective drive and restore the image, then obviously the next step is to install the new drive. A word of caution here: the new drive must be at least as large as the original. If ddrescue runs out of space, it will fail at the very end, even if it is only a few bytes shy.
I prefer a drive that is larger, just in case. Drives of the same nominal size can differ enough between makes and models to cause problems.I've learned this the hard way.Another consideration is the integrity of the image file. When ddrescue has done all it can, you may still have a significant amount of errors. The terminal window that you started the rescue process in will display the number and size of the errors when ddrescue has finished running. If there are any, it is possible that the damage could be enough to render Windows unstable when cloned to a new drive.depending on where the damage is.
Sometimes running CHKDSK and SFC on the new drive afterwards will take care of it.sometimes not. It's a judgment call at this point. If the errors are significant, you may be better off proceeding with a fresh Windows install and a data transfer/recovery from the rescued image (see Part 3). As you can see in this screenshot, ddrescue failed to recover 512 bytes. Depending on which file, if any, this 512 bytes is from, this may, or may not be a problem.So, assuming everything is OK, install the new drive, connect the USB drive containing the image file, and boot up Parted Magic again.
Browse to the image file on your USB drive and open a terminal (File-Terminal). Now, we have a few options on how to image the new drive. I usually use the.nix dd command. Dd is very similar to ddrescue, Here is the command. Code:# dd if=test.img of=/dev/sdaIn this case, “if” is the input file (our image file of the entire old drive in this case), and “of” represents the output file (the entire new hard drive).
Again, be sure to triple check your device names, especially if you have rebooted. They may be different now.This will take a while, and dd doesn't really provide any progress info, so be patient. When the process is finished, reboot and you should be good to go.You can also use ddrescue to image to the new drive instead of dd if you prefer.
Part 2b: Cloning directly to a new diskNow, knowing what we do about ddrescue so far, it is entirely possible to rescue directly from one drive to another, rather than to an image file. Again, be sure to make sure the new drive is an appropriate size as mentioned earlier. Both drives must be connected to the machine that is running linux, either natively or from a live environment like Parted Magic.Using the command from Part 1 to view the attached block devices, determine the correct names for the drive to be rescued and the drive to be imaged to.
Be careful here. If you get this wrong, you could easily image the wrong device to the wrong device, and have a real problem on your hands. Again, the command is. Code:ddrescue -d -f -r3 /dev/sda /dev/sdb /media/PNYusb/rescue.logfileNote that here we need to use a third drive (flash drive in this case, mounted at /media/PNYusb) on which to store the logfile (rescue.logfile in this case).
You can store the logfile anywhere to which you have write access, just not to either of the two drives involved in the imaging process. And again, the same caveats apply to the -r3 switch as in the example from Part 1.Finally, a note about resizing partitions after restoring an image to a new drive that is larger than the original. For example: the failing drive that you rescued was 500gb; the new drive that you used is 750gb. After the restore process, you will now have a 750gb drive with 500gb used, and 250gb as unpartitioned space. You have a few options here.
Part 3: Working with image filesMany times we need to use ddrescue to create an image for file recovery purposes, rather than use it to replace a failing disk. Or we discover after the image is finished, that ddrescue reports too much damage to justify attempting to clone it to a new disk and hope that Windows will have enough integrity to operate.
So, how do we then use the image files to retrieve the data contained therein?Actually we have a few options here. Firstly, some file recovery tools will support working with these image files directly, R-studio for example. So, you may be able to point your recovery software to the image file and go to work.Another option is to mount the image file using linux (either natively or from a live environment like Parted Magic) using the mount command. For a quick primer on mountpoints, please refer to Post# 8 of this thread.In order to successfully mount the image, we need to know if the image file is a whole disk image (/dev/sda) and/or contains multiple partitions.
If the image file is of a single partition (say /dev/sda2), than this process becomes much simpler. This is why I made the earlier statement.
Click to expand.We will cover this scenario first.Part 3a: Working with image files containing a single partitionWith Parted Magic booted and your image file available (from USB disk, etc), we first need to create a suitable place to mount the image file. Open “File Manager” from the Parted Magic desktop, and browse to the location of your image file, As you can see from the screenshot below, I have an image file named “partition.img” stored on my attached USB hard drive. This is an image file I created of the Windows8 partition only (/dev/sda1, rather that /dev/sda) on my guinea pig laptop.Next I will create two new folders on the USB drive: One named “mountpoint” in which to temporarily mount the image file, and one called “recovery” in which to copy and store the recovered files from the mounted image. Notice the two new folders in the screenshot:Next, we just need to issue the proper mount command. Again, use File-Terminal to open a new terminal session. Then enter this command.
Code:# mount -o loop,ro partition.img mountpointThis will temporarily mount the image file in the “mountpoint” directory that we created. Note: The “ro” switch mounts the image as read only. You could explicity specify the filesystem type by using the “-t ntfs” switch as well, but the mount command is pretty good at automatically determining this.Simply browse to that directory, and you should see the contents of the Windows8 partition we rescued.Now you can simply copy the files you need to the “recovery” directory we created earlier. When finished, simply unmount the image file with this command.
Mount points can be kind of confusing. At the most basic level (ignoring fstab, automounting, etc), when.nix first boots, the only file system it is aware of is the file system contained on the root partition which contains the OS (designated as /). In order to use any other file system (another partition, cdrom, USB drive, floppy, etc), it needs to be attached to a place in the current filesystem that the OS already knows about. This is the mount point. Most often, this is a directory created in /mnt.It’s kind of like hooking up a stereo receiver. The receiver has input jacks on the back to plug the components into (CD player, cassette deck, turntable, etc.). The receiver cant use any of these components however, until the patch cables are plugged into the corresponding input jacks in the patch panel on the receiver.
Click to expand.Mounting an image containing multiple partitions is similar to attempting to plug multiple components into the same input jack on the stereo receiver. Here's what happens when you try this.
This screenshot is when I attempted to mount an image file (test.img) that contains multiple partitions:Fear not, there is still a way to mount the individual partition(s) contained in the image file. What we need to do is to tell the mount command where within the image file it needs to look to find the partition we are interested in. We do this by specifying an offset.In order to determine the offset of the partition in question, we use a command line tool called parted. Again, using the terminal with your working directory being the one that contains you disk image, type the following command. Code:# mount -o loop,ro,offset= test.img mountpointThere we have it.
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When I open the “mountpoint” folder where we just mounted the image, I'm presented with the Windows8 partition contained in the full disk image. Now it's just a matter of copying the files I want to another folder before I unmount the image.Again, you can see why it is much easier to have recovery software (like R-studio) that can open these whole disk images for your; and why it is easier to mount single partition images (as opposed to whole disk images) for file recovery.Anyway, that's the basics. Maybe this will help some to better take advantage of the great tools that are ddrescue and Parted Magic.Finally, as an aside, I would encourage anyone who finds Parted Magic as useful as I do, to. I am not affiliated with the project in any way, but I really believe that it is worthwhile, and would like to see it continue.
Click to expand.Mount points can be kind of confusing. At the most basic level (ignoring fstab, automounting, etc), when.nix first boots, the only file system it is aware of is the file system contained on the root partition which contains the OS (designated as /). In order to use any other file system (another partition, cdrom, USB drive, floppy, etc), it needs to be attached to a place in the current filesystem that the OS already knows about. This is the mount point.
Most often, this is a directory created in /mnt.It’s kind of like hooking up a stereo receiver. The receiver has input jacks on the back to plug the components into (CD player, cassette deck, turntable, etc.).
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The receiver cant use any of these components however, until the patch cables are plugged into the corresponding input jacks in the patch panel on the receiver.So, for example: If I had a disk partition that contained all of my music (say sda5 for this example), and I wanted to work with the files in that directory; I would need to mount it first. I would create an empty directory ( /mnt/music in this case) as a point which to attach the filesystem contained on my sda5 music partition.
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I can then explicitly mount the partition with the mount command. Something like this. Code:# mount /dev/sda5 /mnt/musicI can then work with the files on that partition by navigating to /mnt/music. If I wanted to have this partition mounted automatically at boot, I would put an entry for it in a text file called fstab (located at /etc/fstab). Most modern distros take care of this for you, including automatically recognizing and mounting new devices when they are plugged in.If you wanted to see information about what filesystems are currently mounted on your system, run this command. I have a question.Using ddrescue for the first time (I've always just used clonezilla in the past.)I've had it running for about 7 hours now and so far it's only processed about 17 GB out of 1000 GB. Is it normal for ddrescue to take that long?
(I set retries to 0, btw)The drive was giving I/O errors when I tried to look at it in the partition editor, and the partition table is just plain gone. I figured with the I/O errors I should probably get an image first and work with that, but if my math is correct it's going to take somewhere around 17 days just to get the image.Should I just say f. it and ship it off to 300DDR?