[linux-lvm] Mirroring my install. Lots of problems !

Luca Berra bluca at comedia.it
Fri Jan 19 07:12:11 UTC 2007

On Mon, Jan 15, 2007 at 10:42:26AM +0100, Georges Giralt wrote:
>The conversion was a failure, because the tools asked for a THIRD disk in order
>to mirror the VG. Funny. I thought GNU/Linux was clever, I was wrong. How come
>HP-UX or Aix can do LVM mirror on 2 disks and not Linux ? (the corelog option
>is also an issue, as reconstruction will take place at every reboot which occur
>often as this is a home box, not a server)
i am still waiting for the lvm mirror interface to settle before trying
to use it, so i cannot comment...

>So I decided to try a more complex approach : Create a mirror using the mdtools
>(mdadm) and turn this into a VG. My plan was as follow :
>1) create a critical mirror using mdadm with only one copy active on hdb2 repeat
>with hdb3.
>2) pvcreate md0 and md1
>3) add md0 to vg0 and md1 to vg-ext
>4) pvmove all vg0 lv to md0 and all vg-ext lv to md1.
>5) vgreduce vg0 to remove hda2 and vg-ext to remove hda3
>6) add hda2 to md0 and hda3 to md1 and force re-sync
>7) have a beer, and enjoy.
this is the best part of your plan :)
>Again, a disaster. I CAN'T add an md to a vg and have the vg work. I've tried to
>do it using plain md0 to pvcreate, partitionning md0 to create md0p1 and
>pvcreate this (it's impossible, as there is no /dev/md0p1 device...)
can you please be more verbose as to why you can't add an md to a vg
eg showing logs and output of lvm commands with verbose options.
i usually pvcreate md devices without any problem.


Luca Berra -- bluca at comedia.it
        Communication Media & Services S.r.l.
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