[DRBD-user] Clairifcation on primary/primary

[Rus Foster]

Hi,
I've been reading a lot of documentation and managed to get myself a bit 
confused so wondered if some kind sole would just point me in the 
correct direction

 I'm trying to setup a two node cluster with the idea of if node1 writes 
to /home the file can be accessed on node2 but I want both nodes to have 
the ability to write to the device at the same time. I've setup a drbd 
device and set allow-two-primaries; in /etc/drbd.conf.  On both nodes 
I've run

drbdadm primary all

to set to primary

I then mounted /home on both nodes (rw) and if I touch a file on one 
node it doesn't appear on the other.

As such can someone confirm

Is this even possible with drbd handling the file locking for me or do I 
have to look at setting up GFS to get this functionality. Googling has 
chucked up a bit but I've ended up confused and going around in circle

Thanks

Rus