[linux-lvm] (no subject)

[linux-lvm] (no subject)

[Jean-Luc Coulon (f5ibh)]

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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

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Re: [linux-lvm] Converting from LVM to LVM on RAID1 (WAS: no subject)

[Jean-Luc Coulon (f5ibh)]

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Sorry, I forgot the subject

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

> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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Re: [linux-lvm] (no subject)

[Luca Berra]

On Sun, Jul 03, 2005 at 06:56:45PM +0000, Jean-Luc Coulon (f5ibh) wrote:
>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

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 -- bluca@comedia.it
        Communication Media & Services S.r.l.
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Re: [linux-lvm] Converting from LVM to LVM on RAID1 (WAS: no subject)

[dean gaudet]

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