[DRBD-user] Adding disk space

Lars Ellenberg lars.ellenberg at linbit.com
Tue Jul 10 13:15:42 CEST 2007

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

On Mon, Jul 09, 2007 at 11:47:24AM +1000, Dimitri Volski wrote:
> Hi,
> I want to add some space. I have already upgraded the slave to have 
> 900GB, while the master (and the actual storage) is 300GB.
> Master and slave are mirrored. Would it be a problem if I disconnect 
> DRBD, make Slave primary, then do a resize2fs on Slave to match its 
> 900GB, then upgrade Master to have 900GB as well? Or is it still safer 
> to copy the data to a third server, then recreate the DRBD mirror from that?

howto resize a file system on drbd:
 starting point:
  server A          server B
  300GB, Primary      300GB, Secondary
 hardware upgrade:
                      add storage to e.g. 900GB 
                      start drbd again

                      in case drbd is on top of an LVM LV,
                      you need to lvresize now.

                      otherwise, drbd should already know that its
                      physical storage is much larger now.

 now we should be at
  300GB, Primary      300GB, Secondary [on 900GB lower level disk]
        drbd is actually still 300GB, the nodes "agree" to the smaller
        backend storage.

 do a switchover
  300GB, Secondary    300GB, Primary [on 900GB ll-disk]

  add storage ...
  restart drbd
 we are now at
  300GB, Secondary [900GB] -- 300GB, Primary [on 900GB ll-disk]
 tell DRBD to re-negotiate the device size:
  drbdadm resize all
                      drbdadm resize all

                      grep drbd /proc/partitions 
  grep drbd /proc/partitions

   ok, looks good, now tell the file system:
                      resize2fs /dev/drbdX
all done, and without service downtime, even.


: Lars Ellenberg                            Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH      Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe    http://www.linbit.com :
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