> On Oct 27, 2020, at 11:08 AM, Dave Wade G4UGM via cctalk
> <cctalk@classiccmp.org> wrote:
>
> ...
> I remember when doing standby power generator tests we had to remember to
> off-line all the drives at end of job, other wise they all tried to rewind at
> the same time....
> .. and the generator could comfortably do two, stuttered a bit with three,
> but on the first test as the fourth flicked in there was a big "bang" and
> lots of flapping of tape, plus lots of cursing from our Site Engineer.,,,,
A similar issue shows up with large collections of disk drives. That includes
modern small HDDs. The motor start surge current is a lot higher than the
steady state current, so starting a row of drives all at once -- or a box full
of 3.5 inch HDDs in a modern storage array -- can cause an overload.
In storage array firmware that's dealt with by spinning up the drives a couple
at a time, fewer at a time if one of the power supplies has failed.
paul
