(no subject)

Hi,

Is there a safe way to convert from a working LVM (with root on LVM) to a software RAID1 including the device where is the existing LVM ?

Regards

Jean-Luc

P.S. : sorry if this message is recevied twice. It seems tthat there is a problem between wanadoo and gmail

Sorry, I forgot the subject

Le 03.07.2005 20:56:45, Jean-Luc Coulon (f5ibh) a écrit :

it's not a good idea, but you could use raid1 without a superblock... did i mention it's not a good idea?

normally you want the raid1 superblock... which lives at the end of the partition. you can't blindly convert an LVM pv to a raid1 device without ensuring the physical extent at the end of the pv isn't in use. i don't see any way to shrink a pv -- so i don't think you'll be able to convert an existing lvm pv to a raid1 device.

however there's nothing stopping you from creating a raid1 device on a second disk (and specify "missing" for the other raid device(s)... see mdadm man page), creating a pv/vg/lv on top of that raid1, then copying the filesystems over... doing grub/lilo/whatever magic... and trying to boot it.

if it works, you can convert the old disk into the second component of the raid.

there's probably several docs already explaining this sort of procedure without lvm involved... (for example there's one supplied with debian mdadm at /usr/share/doc/mdadm/rootraiddoc.97.html)

-dean

create a degraded raid1 array with only the other disk

add the new md to the existing vg

pvmove all lv on the new pv

remove the old (now empty pv)

use dd to make it forget it was a pv

hotadd this disk to the array

L.

Luca Berra -- [email protected]
       Communication Media & Services S.r.l.
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