[linux-lvm] Switch between mirrored master/slave devices

Brassow Jonathan jbrassow at redhat.com
Thu Jul 19 16:33:13 UTC 2012

you could:
1) edit the LVM metadata.  It's not terribly hard and you would not have to wait for a mirror sync.
2) down-convert ('lvconvert -m -1 vg/lv /dev/mapper/mpath3) and upconvert (same as before but '-m +1').  This will require you to sync the whole mirror.

outside of the fact that mpath3 will be used as the standard to sync from after a machine failure, there is nothing else special about being the 'master'.  If you have a better reason than just aesthetics, you could do #1 or #2 above - otherwise, I don't see the harm in leaving it.


On Jul 12, 2012, at 2:35 PM, DacioMF wrote:

> I have a logical volume mirrored between /dev/mapper/mpath0 and /dev/mapper/mpath3:
> # lvs -a -o +devices
>   LV                   VG       Attr     LSize   Pool Origin Data%  Move Log Copy%  Convert Devices                                   
>   vm01-disk            VMMIRROR mwi-aom-   7.00g                             100.00         vm01-disk_mimage_0(0),vm01-disk_mimage_1(0)
>   [vm01-disk_mimage_0] VMMIRROR iwi-aom-   7.00g                                            /dev/mapper/mpath3(0)                     
>   [vm01-disk_mimage_1] VMMIRROR iwi-aom-   7.00g                                            /dev/mapper/mpath0(0)
> The master device (/dev/mapper/mpath0) failed and i repair it without any problem, but now my master device is /dev/mapper/mpath3.
> I want to change my master device back to /dev/mapper/mpath0 again. How can i do this?
> DacioMF
> Analista de Redes e Infraestrutura
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