[DRBD-user] Increasing a DRBD array

Matt Graham danceswithcrows at usa.net
Mon Oct 17 22:19:58 CEST 2011

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

From: Gerald Brandt <gbr at majentis.com>
> Florian Hass wrote:
>> Gerald Brandt wrote:
>>> 7. fdisk and add the disk to the RAID array on primary and
>>> secondary
>>> 8. grow the RAID array on the primary and secondary
>>> 9. expand the file system on the primary only
>> Not quite. :)
>> Your DRBD uses the MD RAID as its backing device, doesn't it?
>> That means you'll have add the drive and resize your RAID first, then
>> you can resize your DRBD, and then expand the file system.
> Definitely built on top of the RAID.  I'm a bit confused by your
> answer though.  Step 8 grows the RAID array, and I don't have a step
> to grow DRBD.  Does that mean I'm missing something?

8. mdadm --grow /dev/md0 (other mdadm options)
   Do that on both machines.
8.1 (on secondary) drbdsetup /dev/drbd0 resize
8.2 (on primary) drbdsetup /dev/drbd0 resize
   The softRAID is below the DRBD device.  Once the softRAID is
   larger, the DRBD device needs to be informed of this fact.
   When making arrays/devices larger, you go bottom-up; you make
   the hardware changes first, then softRAID changes, then DRBD
   changes, then filesystem changes.
9. (on primary) resize2fs /dev/drbd0

(If this doesn't work as written, it should be pretty close.  The main problem
is that all of the DRBD systems are using hardRAID, while the softRAID systems
aren't using DRBD, so I've done all these things and had them all work, just
not all on the same cluster pair.)

Matt G / Dances With Crows
The Crow202 Blog:  http://crow202.org/wordpress/
There is no Darkness in Eternity/But only Light too dim for us to see

More information about the drbd-user mailing list