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I mistakenly deleted some important zip files from my micro-sd card. I want to do data recovery on my micro-sd card. Before doing that I want take image backup of my sd card data, so that I can have backup of my micro-sd card data in case of any crash. From the link askubuntu I came to know that dd_rescue command will do the job.

This link GNU ddrescue Manual provide few examples for how to do data backup. But I couldn't find the exact command to take data backup from sd card to a image file.

What command I need to provide to take image backup of my micro-sd card?

Thanks for the support

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Arivarasan L
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1 Answers1

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Since you have no errors on the device you don't have to use "dd_rescue". "dd" is sufficient.

I don't know your system configuration. Therefore I suppose your SD card is device /dev/sdx. To create an image using dd please enter the following commands:

dd if=/dev/sdx of=backup-image.img

It's a good idea to unmount the partitions of the SD card before.

I hope this helps?

tpf
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  • when I mount my device and entered the command "df -h", it shows /dev/sdb 3.7G 528M 3.2G 14% /media/47AA-11EF. When I unmount my device it doesn't show the /dev/sdb. How could I run the dd command after unmounting my device ? – Arivarasan L Aug 29 '13 at 06:09
  • If you've unmounted the SD card the command "df -h" doesn't show it anymore. – tpf Aug 29 '13 at 06:34
  • Are you sure about /dev/sdb ? This is the device. When mounted "df -h" should show /dev/sdb1 instead. What do see if you run "sudo fdisk -l"? – tpf Aug 29 '13 at 06:36
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    If "sudo fdisk -l" is showing the device (/dev/sdb) and its partitions you can start the command dd if=/dev/sdb of=backup-image.img to create an image. – tpf Aug 29 '13 at 06:38
  • I got "Disk /dev/sdb: 3964 MB, 3964141568 bytes 122 heads, 62 sectors/track, 1023 cylinders, total 7742464 sectors" when i run "sudo fdisk -l". Shall i proceed by the command "dd if=/dev/sdb of=backup-image.img" after unmounting the device? – Arivarasan L Aug 29 '13 at 06:45
  • Yes, please. But I've never seen a proper disk without partitions. Is there not a row like this /dev/sdb1 16 31116287 15558136 c W95 FAT32 (LBA) ? Do you see a message like this after running the fdisk command: Disk /dev/sdb doesn't contain a valid partition table ? I think your partition table is corrupt. – tpf Aug 29 '13 at 07:53
  • The dd command runs anyway. – tpf Aug 29 '13 at 07:55
  • I run the dd command and got a backup-img.img file, but when i try to mount it with the command "sudo mount backup-image.img /mnt -t iso9660 -o loop" i got " wrong fs type, bad option, bad superblock on /dev/loop0,missing codepage or helper program, or other error" – Arivarasan L Aug 29 '13 at 08:02
  • there is nothing displayed like "/dev/sdb1 ..." when I run sudo fdisk -l. – Arivarasan L Aug 29 '13 at 08:06
  • I dont't think you have an ISO file system on your SD card. Its mostly FAT/FAT32 or ext2/3/4 if used with Linux only. What happens if you plug-in the SD card in the reader? Can you access files in the location /media/47AA-11EF ? – tpf Aug 29 '13 at 08:45
  • If you like to use the created image you have to call fdisk -l backup-image.img first to show the partition table. In the partition table you can see the offsets you must enter as parameter when mounting as loop device. But if you can't see a partition table your card is damaged. – tpf Aug 29 '13 at 09:34
  • A damaged partition table could be repaired by "testdisk". See this manual link. After that or additionally you can use dd_rescue or PhotoRec with the image to save lost content. – tpf Aug 29 '13 at 10:25
  • thanks tpf for your support, I create backup image with the dd command and mounted it by the command "sudo losetup /dev/loop0 /home/ars/backup-image.img". Finally I run recovery command "sudo scalpel /dev/loop0 -o myfiles". since my zip file is around 350MB it fails to recover it. – Arivarasan L Aug 29 '13 at 10:32
  • If the files are very important you could give "foremost" or other tools a trial: link – tpf Aug 29 '13 at 13:14