Staggered wake-up from standby for SATA disks

[Nuno Subtil]

Greetings,

I have a small storage server with several SATA drives running ZFS on
9.2-RELEASE. Due to various issues (mostly dealing with noise and
power consumption), the system was spec'ed with a power supply that
requires spinning up the disks one by one. This problem is easily
solved for boot-up by enabling power-up in standby on the drives and
setting CAM_MAX_HIGHPOWER=1, which seems to work fine.

I'm also interested in allowing the drives in the ZFS pool to spin
down after a period of inactivity. However, it sounds like
CAM_MAX_HIGHPOWER doesn't help for this scenario (or maybe I'm wrong?)
--- as far as I can tell, multiple drives would be allowed to spin up
from standby at the same time.

Is there an equivalent mechanism for staggering wake-up from standby
on SATA disks?

Thanks,
Nuno Subtil