[Observium] Disk i/o statistics

Hi all,

We are currently moving our observium server from an old community edition (0.13.10.4585) to a new powerful server running Professional edition (0.14.4.5391). On the new one, all disk i/o statistics for server devices don't appear in the web interface. After some research, I found that rrd files for disks i/o are not generated. For example, same server monitored by old instance: http://pastebin.com/gF7RA9bU and on new one: http://pastebin.com/Y9ePqyst

Maybe I'm missing some new configuration option?

Thanks,

Fabrice