Clone from one hard drive to another of different size:
Backup a drive to another drive dd
Use dd command to image
Backup drive using linux
Linux dd backup drive or Linux disk image dd
This works with Windows 7, Mac OS X, Vista and any Linux.
Note: If you just want to backup or restore your partition table and or the MBR click here.
Creating a hard drive backup directly to another hard drive, or linux backup entire disk.
# dd if=/dev/hda of=/dev/sda conv=noerror,sync bs=4k
This command is used often to create a backup of a drive (/dev/hda) directly to another hard drive (/dev/sda). The device name /dev/hda is typical of an IDE hard drive, the device /dev/sda is typical of a USB disk – key drive. This works only if the destination hard drive (of=) has enough storage to accommodate the source drive’s (if=) filesystem. The advantage of this is that you do not have to mount the hard drive to make a backup and the only reference to hda is in /dev and in the command which is usually in a script in cron. Another huge advantage of using dd to clone one hard drive to another is that this is the only way I know of that copies raw data instead of partitions, so you can clone an encrypted drive or one without partitions.
The option “bs=4k” is used to specify the block size used in the copy. The default for the dd command is 512 bytes: use of this small block size can result in significantly slower copying. However, the tradeoff with larger block sizes is that when an error is encountered, the remainder of the block is filled with zero-bytes. So if you increase your block size when copying a failing device, you’ll lose more data but also spend less time trying to read broken sectors. Tools like dd_rescue and dd_rhelp can provide a more flexible solution in such cases, combining the speed of a large block size for the regions without errors with finer-grained block-copies for regions with errors.
Creating a hard drive backup image or dd command image backup linux.
# dd if=/dev/hda | gzip > /mnt/hdb1/system_drive_backup.img.gz
Here dd is making an image of the first harddrive, and piping it through the gzip compression program. The compressed image is then placed in a file on a seperate drive. To reverse the process:
# gzip -dc /mnt/hdb1/system_drive_backup.img.gz | dd of=/dev/hda
Here, gzip is decompressing (the -d switch) the file, sending the results to stdout (the -c switch), which are piped to dd, and then written to /dev/hda.
To backup or copy a cd to a file with linux using dd is very easy:
dd if=/dev/cdrom of=image.iso bs=2k.