[DRBD-user] Making DRBD see new disk sizes

Cameron Smith velvetpixel at gmail.com
Fri Jan 21 00:32:48 CET 2011

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

This issue came up in a separate thread on a different topic and wanted to
discuss it separately.

I have a two node setup both running 8.2.6

I increased the sizes of the physical disks on both nodes but DRBD is still
only showing the old sizes.

My DRBD meta-data is on it's own external partition and always has been.

How can I have DRBD use the full size available?

Here was my procedure:
I was out of disk space so I took secondary offline, rebuild it's array with
larger disks, reinstalled the OS and built the correct partition scheme,
installed DRBD and ran:

drbdadm create-md r0
drbdadm attach r0
drbdadm syncer r0
drbdadm connect r0

It started to sync to the original primary and completed.

I reinstalled all services and made secondary primary.

I then rebuilt the new secondary with the same larger disks and matched all
to the new primary. I installed DRBD and then ran:

drbdadm create-md r0
drbdadm attach r0
drbdadm syncer r0
drbdadm connect r0

It synced completely.

I have up to date on both but df -h on primary shows the old partition size

You can see the old /dev/drbd1 saw 261G for sda5 and sda5 on new has much
more space (as seen in parted) that is not available when mounted now.

Here is info from primary:

[root at web002 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             9.7G  4.6G  4.7G  50% /
/dev/sda1              99M   18M   77M  19% /boot
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/drbd1            261G  227G   21G  92% /data
[root at web002 ~]# parted
GNU Parted 1.8.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print

Model: DELL PERC 6/i Adapter (scsi)
Disk /dev/sda: 599GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system  Flags
 1      32.3kB  107MB   107MB   primary   ext3         boot
 2      107MB   10.8GB  10.7GB  primary   ext3
 3      10.8GB  19.4GB  8587MB  primary   linux-swap
 4      19.4GB  599GB   579GB   extended
 5      19.4GB  595GB   575GB   logical   ext3
 6      595GB   599GB   4294MB  logical

(parted) quit
Information: Don't forget to update /etc/fstab, if necessary.

[root at web002 ~]# cat /etc/drbd.conf
global {
  usage-count yes;
common {
  protocol C;
resource r0 {
  syncer {
    rate 110M;
  on web001.example.com {
    device    /dev/drbd1;
    disk      /dev/sda5;
    meta-disk /dev/sda6[0];
  on web002.example.com {
    device    /dev/drbd1;
    disk      /dev/sda5;
    meta-disk /dev/sda6[0];

What can I do to have DRBD see all available space on /dev/sda5???

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