27 Oct
2020
27 Oct
'20
9:33 a.m.
On Oct 27, 2020, at 11:08 AM, Dave Wade G4UGM via
cctalk <cctalk at 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