[DRBD-user] Increasing a DRBD array

Gerald Brandt gbr at majentis.com
Tue Oct 18 14:08:55 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.


Okay, this is my list of what to do, and in what order:

1. remove the primary from DRBD
2. add the physical disk to the primary
3. add the primary back to DRBD and allow resync.
4. remove the secondary from DRBD
5. add the physical disk to the secondary
6. add the secondary back to DRBD and allow resync.
7. fdisk and add the disk to the RAID array on primary and secondary
8. grow the RAID array on the primary and secondary (while mounted or not mounted?)
9. drbdadm resize on the primary (can this be done while drbd is in use?)
10. expand the file system on the primary only (via Citrix XenServer (iSCSI))

That sounds about right.  As long as I don't lose data. (yeah, backups.  That's left up to my client, but becomes my problem if they failed.)


----- Original Message -----
> From: "Florian Haas" <florian at hastexo.com>
> To: drbd-user at lists.linbit.com
> Sent: Tuesday, October 18, 2011 3:53:11 AM
> Subject: Re: [DRBD-user] Increasing a DRBD array
> 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.
> Cheers,
> Florian
> --
> Need help with DRBD?
> http://www.hastexo.com/knowledge/drbd
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user

More information about the drbd-user mailing list