FC6 - Software Raid (after install)

[Bruno Wolff III]

On Fri, May 25, 2007 at 01:28:03 -0500,
  "M. Lewis" <cajun at cajuninc.com> wrote:
> 
> I'm looking for a HOWTO to setup software raid (RAID1) after the 
> install. I have found this thread:
> 
> http://marc.info/?l=fedora-list&m=115108639325376&w=2
> 
> which seems like a reasonable setup during the install, but what I'm 
> needing to do is setup RAID1 on a working system. Duplicate the 
> partitions, mirror the drives, etc.

That might be a problem as software raid uses to use a few blocks at the end
of partitions to track information about the array. The man page for mdadm
says that you can assemble arrays without superblocks, but I don't know if
that takes care of all of raid's disk needs or how well that will work
if the raid devices need to run as part of the boot process.
If you want to switch a file system to part of a raid array in place, you'll
probably need to shrink the file system slightly (which is possible with
some file systems, switch the partition type to software raid, create
a degraded array with that partition, force it to run, add in the new
array element and once it has syncd you will probably be good to go.
You will want to find some reliable documentation on how much space
software raid uses at the end of the partition.