[DRBD-user] DRBD on LVM-> Disk Upgrade

Jürgen Scholz juergen at kernkraft400.com
Wed Aug 19 23:22:55 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


> I was thinking I could make sure once system has all the volumes on  
> one
> disk in secondary, detach DRBD and remove the Disks. Put in new disks,
> create a new logical volume group recreate logical volumes of the same
> size and let DRBD synch back to the new disks.
What you're suggesting would take a full resync. I suggest:
   1. Let one machine be the secondary for all drbd resources. See that
      it stays this way by disabling your CRM. Work on this machine.
   2. Put in your new disks.
   3. Make a raw copy of your old disk to the new one with dd.
   4. Remove the old disk.
   5. Extend your LVM partition.
   6. pvextend your PV.
   7. lvextend your LVs. (If you're using internal meta-data you'll have
      to move that first. Perhaps somebody else can help determining the
      necessary parameters for dd. I use externat metadata and never had
      to deal with this.)
   8. Do: drbdadm adjust all

   9. Do the same for the other machine.

Drbd will then notice that the underlying blockdevice grew and a partial
sync will start.
I've done this a few times. It always worked. I hope I did not forget
anything. Please double check and test in a lab first!

@LINBIT: I've always wondered with how little consideration internal
metadata is recommended for new systems. I've read here for quite a  
and it seems many people run into problems with internal metadata which
wouldn't exist with external md.
Addistionaly an external meta-data disk can be moved to another spindle
for performance reasons. This doesn't work with internal, or does it?

Maybe you could think about suggesting external meta-data for all  
where the creation of a separate partition/LV is no problem.
- Even if you don't agree with me i would like to hear about why  
is recommended.

Thank you for reading!

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