mount a 2nd virtual disk on VM running Debian

Hi team,

I'm coping a little issue today.

I am running vCenter 5.1 with 2 ESXi hosts running vSphere 5.1 each (vCenter is also in a VM box on one of my 2 hosts)

I've many VM all running Debian squeeze 6.06 (i don't think this is the issue but..)

In one box (running Debain as OS) I've added a virtual disk via vSphere client connected to vCenter.

no pb, it was done in 3 clicks.

After, I wanted to mount it via my debian console with SSH

with something easy like that : mount /dev/sdb /mnt/data

(the first disk is on /dev/sda)

"I got this error message : mount: you must specify the filesystem type"

and even if I specify -t ext3 for example I got that :

Can't I mount my virtual disks this way ?

Thx buddies.