On Fri, 2021-06-18 at 08:58 +1000, Cameron Simpson wrote:
> On 17Jun2021 12:15, Patrick O'Callaghan <pocallaghan@gmail.com>
> wrote:
> > On Thu, 2021-06-17 at 07:20 -0300, George N. White III wrote:
> > > > The technical specifications of the drives should mention
> > > > startup
> > > power
> > > management. There may also be some power management in the dock.
> > > I've noticed that it is becoming more difficult to find detailed
> > > documentation
> > > of add-on hardware. At one time you could open the box, identify
> > > key
> > > IC's
> > > and get the spec. sheets, but now you may find a general-purpose
> > > CPU.
> > >
> >
> > It's a cheap dock so probably not easy to find any technical
> > documentation. One thing I might try is to swap the two drives
> > around
> > just to see if it's always the same one that causes the delay.
>
> On the subject of power as raised by George, I had trouble with too
> many
> USB bus powered drives on the home server. A powered USB 3.1 hub
> helps
> me out there. Doubtless it has its own limits.
The dock has its own power supply.
Is this a full-featured dock with USB and monitor outlets or a
disk only dock?
It might be useful to compare the rating of the power supply with
the peak load from the drive spec sheet. Older high RPM drives
had quite high startup draw. Does the power supply have multiple
voltages or just one voltage (the latter requires conversion in the
hub)? If the power supply can't meet the startup requirements of
two drives then it must be doing some power management. The
simplest approach would be to provide a delay before starting
one of the drives.
Amazon has a popular Sabrent disk-only dock -- one review notes:
Cons
- when using 2 drives and plugging or unplugging one drive BOTH
go offline, at least temporarily. NOTE: Seems to be a common limitation
to all these docks. I have yet to find one that does not behave this way.
Must be the way the SATA bus controller is designed.
- when plugging in 2 drives, they mount sequentially, meaning you
have to wait for one to mount before the other will