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Multiboot backup DMG


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Hi all.


So after countless weeks of messing with OS X and trying to multi boot working I have succeeded for the most part but now have a puzzling question. Seeing how it was suh a pain in the ass to get this all working(os x 10.5.8 + win 7 rc + ubuntu 9.04) i'd really hate the reformat process. Is there a way to take this brand new multiboot hard drive and make a DMg of it that I could just restore later that would simply work?

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  1. Buy a new hard drive identical to or larger than the old one in size.
  2. Install said hard drive (even temporarily).
  3. Boot any of the many Linux emergency CDs/DVDs.
  4. Identify which drive is which. In the below, I'll assume your current drive is /dev/sda and the new one is /dev/sdb.
  5. Type "dd if=/dev/sda of=/dev/sdb".
  6. Wait. Wait some more. Wait still more. Get a good night's sleep. Wait some more. (This process takes, in all probability, several hours. Unfortunately, there's no status display.)
  7. If desired, test the backup by removing the original and booting the backup.


I realize this may not be what you want; it's costly and awkward. It's also very effective and it's almost guaranteed to work, provided you're careful with your drive IDs when you use dd. (If you're not, you might wipe out your working system.) There are faster ways to do the backup, but each method of speeding up the process slightly increases the risk of having something go wrong that will render the backup either useless or difficult to restore. Since a multi-boot configuration will require several different speedup techniques, odds are one of them will fail at restore time.


If you want to go for something that'll take less storage space and/or time, the basic procedure is to use OS- or filesystem-specific tools to back up each partition. You'll then need to back up your MBR's boot loader ("dd if=/dev/sda of=backupfile.mbr bs=440 count=1" in the aforementioned Linux emergency disk, or use the same command but with /dev/disk0 rather than /dev/sda in OS X). You may need to back up the boot loaders in each boot partition, too (a similar command works, but you'll need to specify the boot partition rather than the MBR, and you'll probably need to back up more data, as in "bs=512 count=2" to back up two whole sectors). Alternatively, you can get read up on whatever boot loader(s) you use so that you understand them well enough to restore them when the time comes. Unfortunately, this task is a confusing one; boot loaders are tricky and finicky things.


The restore process is to partition your new disk (you may need to ensure that some or all partitions are bigger than their originals), reverse the individual filesystem backup process, and restore the boot loader(s).

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