OpenFiler drbdadm create-md cluster_metadata exited with code 40

Hi everyone

I am trying to configure DRBD using Openfiler . I followed the links
http://www.howtoforge.com/installing-and-configuring-openfiler-with-drbd-and-heartbeat
http://www.crebelo.co.uk/openfiler-guide-print.php

in both cases I have got the following error  
[root@filer01 ~]# drbdadm create-md cluster_metadata
md_offset 534638592
al_offset 534605824
bm_offset 534589440

Found ext3 filesystem
      522112 kB data area apparently used
      522060 kB left usable by current configuration

Device size would be truncated, which
would corrupt data and result in
'access beyond end of device' errors.
You need to either
   * use external meta data (recommended)
   * shrink that filesystem first
   * zero out the device (destroy the filesystem)
Operation refused.

Command 'drbdmeta 0 v08 /dev/sda3 internal create-md' terminated with exit code 40
drbdadm create-md cluster_metadata: exited with code 40

Please help
Thanks
Kunal