>>>>> "d" == Don <d...@blacksun.org> writes: >>>>> "hk" == Haudy Kazemi <kaze0...@umn.edu> writes:
d> You could literally split a sata cable and add in some
d> capacitors for just the cost of the caps themselves.
no, this is no good. The energy only flows in and out of the
capacitor when the voltage across it changes. In this respect they
are different from batteries. It's normal to use (non-super)
capacitors as you describe for filters next to things drawing power in
a high-frequency noisy way, but to use them for energy storage across
several seconds you need a switching supply to drain the energy from
it. the step-down and voltage-pump kinds of switchers are
non-isolated and might do fine, and are cheaper than full-fledged
DC-DC that are isolated (meaning the input and output can float wrt
each other).
you can charge from 12V and supply 5V if that's cheaper. :)
hope it works.
hk> "okay, we've waited 5 seconds for additional data to arrive to
hk> be written. None has arrived in the last 5 seconds, so we're
hk> going to write what we already have to better ensure data
hk> integrity,
yeah, I am worried about corner cases like this. ex: input power to
the SSD becomes scratchy or sags, but power to the host and controller
remain fine. Writes arrive continuously. The SSD sees nothing wrong
with its power and continues to accept and acknowledge writes.
Meanwhile you burn through your stored power hiding the sagging supply
until you can't, then the SSD loses power suddenly and drops a bunch
of writes on the floor. That is why I drew that complicated state
diagram in which the pod disables and holds-down the SATA connection
once it's running on reserve power. Probably y'all don't give a fuck
about such corners though, nor do many of the manufacturers selling
this stuff, so, whatever.
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