You might find this little writeup useful.  It's a little dated but I can 
vouch that it works.

> http://www.dell.com/downloads/global/power/1q04-hul.pdf




Samuel Halicke wrote:
> On Jun 19, 2008, at 11:50 AM, Timmy wrote:
> 
>> [snip]
>>
>> So, I face a problem:  How to REBUILD / CLONE sda to sdb with Linux 
>> command mdadm??  :((
>>
>>
>> Timmy
> 
> The "simplest" route is to just use dd(1):
> 
> dd if=/dev/sda of=/dev/sdb bs=1M conv=notrunc,noerror,sync 2>&1 | tee 
> /tmp/dd-errors.log
> 
> This will create an exact, bootable clone, including partition tables 
> and UUID. It may take a long time, and there is no progress indicator 
> with dd, but it works. If there are errors, you can check the file tee 
> writes. See the dd manpage for more details.
> 
> Other alternatives include partimage, available here: 
> http://www.partimage.org/Main_Page -- and also, the mdadm command itself 
> -- the short version: set up RAID 1, partitions to Linux raid 
> autodetect, put the first drive (your everyday drive) as the first in 
> the set and the second as the mirror. The md driver should automatically 
> rebuild the mirror for you. Just make sure you partition the disks the 
> same way. There's plenty of information on the web about working with 
> md/mdadm.
> 
> -- 
> Samuel Halicke        [log in to unmask]
> FNAL/CD/SF/FEF        FCC/252/U
> (T): 630.840.4308    (P): 630.266.0042