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Old 08-14-2001, 09:36 AM   #1
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Post dd mirror command for 2 OSes


We need to mirror a ~4.5 GB HD onto a ~6GB HD, both IDE, using dd. There are a few issues involved. The source disk has two operating systems - Win98 and a non linux Unix. The target disk is an opened, new HD. How does the target HD need to be formatted? After the source hard disk is copied to the target, file recovery tools should be able to run on the 6GB disk. This means all the information from the Win98 partition needs to be copied exactly, including the FAT and any other things needed. Also, is it possible to copy over bits from the reserved sectors of the source hard drive used for bad sectors? How can these be accessed?

The target hard drive should be just like the source. It should have the same MBR. Does the size difference matter? Does it matter what OSes the source drive is running?

What is the dd command to type to copy the disks the way we want? I believe there also needs to be an extra flag to tell dd not to stop if it encounters an unreadable bit?

Second, the computer that the hard drives are hooked up to does not currently run linux. A rescue floppy with dd on it will be needed. How can I make such a floppy disk with RedHat 6.x?

Old 08-14-2001, 06:06 PM   #2
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Usually I'm using partimage to nibble partitions. might be beneficial to look into TCT at The Coroners Toolkit really is a (perl-based) forensics toolbox, it has some nice tools that can find any "dead" data as well.

dd if=/dev/hda of=/dev/hdb bs=512
* the bs= is for blocksize, so it nibbles per sector.
* add "count=1", set if= to the bootable partition, and of= to mbr.dat to just have the bootsector.

The only problems with dd IIRC, is that the disks need to have the same geometry, and shouldnt have disk activity going on.
Another way might be in using dump on each partition, and restoring tru a pipe to the other disks partitions, but Ive never used that.

To make a bootdisk, there should be mkbootdisk or so. U could also go for a 1 floppy distro like the excellent tomsrtbt, use ure RH cd as rescue cd, or use a fullblown distro like finnix (bootable cd).

HTH, somehow.


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