[Solved]my disk don't go standby

i have installed OMV on my raspberry 3, it works very well and smooth, i'm very happy for this. but i have a problem, i have connected an hard disk toshiba model mq01abf050 to an hub for OMV, all works well but that disk doesn't go in standby mode when it is not in use, the disk always turns.
how could i set it?

i solved with a reboot of raspberry, now the disk goes on standby