[TriLUG] mdadm ( or dmraid? )

[Brian McCullough via TriLUG]

Folks,

I'm afraid that the memory is gone. ( or at least far enough away that I
can't find it )

I am trying to create RAID 1 mirrors of some existing partitions in my
system.

First of all, is mdadm still "preferred" or should I be looking at
dmraid?  Perhaps preferred is not the word, how about "used?"

In any case, I attached a new drive to the system, used gdisk to create
partitions that matched existing ones, and then ran: "mdadm --create
--verbose /dev/md0 --level=1 --raid-devices=2 missing /dev/sde1"

This was successful.

I then, being the paranoid person that I am, duplicated one of the
existing partitions into some spare space, and ran: "mdadm --add
/dev/md0 /dev/sdg1"

When I try to mount either /dev/sdg1 or /dev/md0, the system refuses
with filesystem type failures.

Is this telling me that I can not "convert" my existing partions to
mirrored ones "in place," but must create brand new space for the mirror
( both pieces ), and copy the existing partion into it?


Would using dmraid change any of these answers?


Thank you,
Brian