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When I back up from one hard drive to another with Ghost I can switch those hard drives at will and the computer doesn't seem to mind. When I back up HDD A onto HDD B with dd, HDD B performs slower and blue screens all the time (windows). What is Ghost doing that dd isn't?

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  • Assuming this is some version of windows?
    – soandos
    Commented Nov 25, 2011 at 20:28
  • @soandos yes, I've had this behavior with XP, Vista and 7. I've never tried this type of restore on linux, so I'm not sure if it would happen there too.
    – Mikey
    Commented Nov 25, 2011 at 20:30
  • I'm hazarding a guess, but I think it relates to the hard drive image being implemented differently somehow with Ghost over dd. I've seen similar behaviour (slower performance) when using CCC instead of Acronis on a Mac. Acronis does fine, where the CCC copy is slower.
    – user3463
    Commented Nov 25, 2011 at 22:32

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Ghost actually understands the file system (FAT, NTFS, etc) and just copies the files. It can intelligently avoid free spaces in the partition and can apply compression to save space/speed up transfer.

When the files are restored, they are not put to their original location, but just placed consecutively (for non-special files) as if they're newly created. That's why sometimes a Ghost image restore is the fastest way to defragment a large partition.

dd just sees the whole partition as a giant binary file and copies it verbatim. It will copy all the deleted files and free spaces. It has no built-in compression neither. Thus it is generally slower and unrecommended for large/empty partitions.

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  • Those seem like clear advantages Ghost has over dd, but they don't really explain why the new drive is intermittently problematic since presumably all those inefficiencies are still working against the original.
    – Mikey
    Commented Nov 29, 2011 at 3:25
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    Are the two disks the same model? Maybe check their SMART status? When you use dd to clone the drive, the list of bad sectors maintained by NTFS is copied over as opposed to being recreated. If you actually have bad sectors on drive B, some of the files maybe corrupted and causing the blue screens.
    – billc.cn
    Commented Nov 29, 2011 at 11:02

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