I've got a small server ( 4 drive bays ) with a RAID1 (mirrored) md 
array on two drives that I'd like to convert to RAID5 ( adding two new 
drives -- one active and one as a spare).

I'm starting with 4 drives.  Two active in the current mirror and two 
unused. The process I'm considering:

    Fail and remove a drive from the current md mirror, leaving three 
unused drives
    Create a new RAID5 array
    Add the new md RAID5 device as a member of the degraded mirror
    Wait for mirror to sync (thus copying the existing data to the new 
device)
    fail the remaining drive in the RAID mirror
    remove the old md device
    update GRUB and boot from the new RAID5 device

Does anyone know if md can be used recursively like that?  More 
importantly -- will if cause major problems if I try?  I'm guessing that 
md won't let me do it; but it sure would be easier than moving the files 
by hand.

Dave Alitz