moving stuffs between harddisk

[Man-wai Chang]

the old 5400rpm 20G harddisk (hda) of my linux server is getting.
I have a spare 7200rpm 20G harddisk (hdc).

what's the fastest way of moving everything from the old harddisk to the 
new harddisk? is it:

dd if=/dev/hda of=/dev/hdc bs=1024000

if the 2 disks have different geometry, will it work?


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