DRBD Error

if you find this error : drbdadm create-md [Error]

# drbdadm create-md r0
md_offset 889054060544
al_offset 889054027776
bm_offset 889026895872

Found ext3 filesystem which uses 868216860 kB
current configuration leaves usable 868190328 kB

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 /dev/drbd0 v08 /dev/sda4 internal create-md’ terminated with exit code 40
drbdadm aborting

please insert this command  :

# dd if=/dev/zero of=/dev/sdaX bs=1M count=128