[DRBD-user] format /dev/drbd0

[Simon Ironside]

On 01/05/18 08:22, Roland Kammerer wrote:
> On Mon, Apr 30, 2018 at 02:59:23PM +0300, Ran Shalit wrote:
>> Hello,
>>
>> I've seen in tutorial that we format the /dev/drbd0 block device
>> (mkfs.ext4 /dev/drbd0).
>> Should it give the same result as if we formatted the real device (for
>> example /dev/sdb1)  or are there any differences ?
> 
> When you use a device as backing device for DRBD, you then should never
> ever touch the backing device directly. Just saying. You "have to" (you
> really should) format the DRBD dev, and not the backing device.
> 
> Besides that, "the user visible behavior" should be the same. Obviously
> the DRBD device might be slower because of the replication over the
> network. But it should contain a normal ext4 filesystem...

Most likely difference would be when using internal metadata, the DRBD 
device will be a smidge smaller than the backing device to account for 
this which may cause you problems. As Roland says, don't touch the 
backing device!

Simon