11/10/2023 0 Comments Systemrescuecd dd vs ddrescue![]() The two block sizes are a performance optimization. If you have one spot of bad sectors within the partition, it might be a good idea, to approach this spot from both sides. The output file will just be filled in further and not truncated as with other Un*x tools. You can just continue at any position later. If you interrupt the process of copying, you don’t lose anything. ![]() The data rate drops very low, when errors are encountered. You can write a log file, to see, where all these errors are located. ![]() The output file naturally will have holes in it, of course. dd_rescue instead will try to read and if it fails, it will go on with the next sectors. You can setup a loop device, and repair (fsck) it and hopefully are able to mount it.Ĭopying this partition with normal Un*x tools like cat or dd will fail, as those tools abort on error. You burn it on CD-Rom, just to never lose it again. Now, you want to copy the whole partition into a file. However, you can’t access the files, as the file system is damaged. Just getting all the data off it and retiring it seems to be suitable. Imagine, one of your partitions is crashed, and as there are some hard errors, you don’t want to write to this hard disk any more. If the copying process is interrupted by the user it is possible to continue at any position later. It tries to read and if it fails, it will go on with the next sectors where tools like dd will fail. I have successfully recovered ext3, ext4 and ntfs filesystem partitions using fsarchiver.Like dd, dd_rescue does copy data from one file or block device to another.dd_rescue is a tool to help you to save data from crashed partition. One cautionary note, if your hard drive is dying, you may find it advisable to exercise it as little as possible until you execute the backup (whatever solution you choose to run).įootnote : I'm running Fsarchiver as my principal weekly backup app covering a 17 partition lineup. In theory, at least, this should provide a visibility to any corrupted files as result of your hard drive situation. One of the big advantages in your situation is that the app computes a md5 checksum on all files and folders written to the backup. The app works well with all conventional file systems. Basically, fsarchiver will make a backup image file composed of all of the files / folders in your origination partition. Will this allow me to put the image on a different drive without damaging the existing data on that drive? If so, then this will do perfectly.Īs an alternative to the dd approach, you may want to take look at Fsarchiver as it's bundled to SysRescueCD (a live CD). I've recovered data from a number of failing drives this way, including a RAID0 fakeraid array when one of the drives was going bad and the array could not otherwise be assembled. Once you have the image you can mount it using loopback, or copy to another drive for analysis and possible data recovery. (This gives you a shot at keeping the layout of the filesystem intact.) The "-A" option always writes to the output file, zeroes in the case of read errors. (Though dd_rescue does not like very large block sizes, it will abort on an error if you specify too large a value.) The "-b" option sets a larger block size to speed up copying when there are no errors. For example, if the failing drive comes up as /dev/sdb, you would enter something like:ĭd_rescue -b 2096K -A /dev/sdb sdb-image.img What I usually do in that kind of situation is to use dd_rescue to make an image copy of the entire drive, then work with that for data recovery. So, if anyone could help me out, it would be greatly appreciated. minus a piezoelectric speaker on the circuit board which lost a fight with a soldering iron. After 14 hours of that, I am starting fresh. I am using a USB drive caddy to hold the drives that beeps every 8 seconds. I tried to use testdisk to create an image, and let it run over night, but in the morning, I had a 2G image file (there is at least 100G of data on the drive), so I know it did not work right. Once I am done this, I intend on using sleuthkit or something similar to try and recover what I can. I know which drive is which in drive manager, or /media/ if its mounted. ![]() I know there are going to be errors, so I don't want to have to acknowledge every one. Since the source drive is on its last legs. I do not want to lose any data on the 2 TB drive. I want to recover the 250G drive to a "folder" on the 2 TB drive. I have a 2 TB drive that I use as a data storage/backup drive. I have a 250G drive that is in its death-throws. Sadly most help I found assumes more expertise in Linux that I currently have. Google is great when you have a general knowledge of what you are trying to accomplish. Ok, I have spent the last day trying to figure this out. ![]()
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