Good RAID HowTo

[Brian C. Huffman]

All,

I'm trying to find a good RAID howto on migrating from a non-mirrored
disk to a mirrored configuration both for the root filesystem as well as
others.  

Everything I'm finding is *extremely* dated.  This shouldn't be that
difficult - I've done it w/ Solaris a million times.  :-)  However, I'm
concerned with gotchas in Linux.

Can anyone offer some pointers?  Sorry that this is somewhat off topic
for this list.

Thanks,
Brian