[DRBD-user] Increasing a DRBD array

Florian Haas florian at hastexo.com
Tue Oct 18 10:53:11 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.

On 2011-10-17 22:19, Matt Graham wrote:
>>> 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

There's a "resize" subcommand for drbdadm too; no need to use drbdsetup.
And it needs to be done on one node only. Just do "drbdadm resize
<resourcename>" on the primary while the two nodes are connected, and
you're good to go.

>    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 it's ext3 and if it supports on-line resizing, of course. But that
should be obvious.


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