[rescue] Block size and the single DD - more test results
Steve Sandau
ssandau at gwi.net
Thu Feb 12 16:37:16 CST 2004
> As far as I know, the true meaning of 'dd' has been lost to the mists of
> time, but it likely stood for something along the lines of 'disk
> duplicator' or 'data dumper' or something along those lines. It has no
> real concept of a file, or even a filesystem. dd basically does a
> byte-for-byte copy of a device/slice/partition, it has no concept of
> what is actually on the filesystem. This is a feature. It allowed me
> to use dd to make clones of systems that the underlying OS knows nothing
> about (ie, using linux to make clones of a Windows 2000 installation for
> corporate roll-out, or making _bootable_ backups of my IRIX install CDs
> from linux).
>
I always thought dd was "device-to-device" copy. And the bit-by-bit copy
is indeed a feature. I can use dd to email a boot disk as a floppy
image, or to put a floppy image back on a disk. I've also cloned an AIX
hard drive before I messed with it. dd copied the bootblock and all, so
I could put the image I made back on another herd drive and it was
immediately bootable. I had no way to reinstall the OS, since it was on
an eBay-bought 6611 router. I cracked the passwords without worrying
about damaging the original disk.
SteveS
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