Re: Journaling pointless with today's hard disks?

[H. Peter Anvin]

Followup to:  <[e-mail]>
By author:    "Richard B. Johnson" <[e-mail]>
In newsgroup: linux.dev.kernel
> 
> It isn't that easy!  Any kind of power storage within the drive would
> have to be isolated with diodes so that it doesn't try to run your
> motherboard as well as the drive. This means that +5 volt logic supply 
> would now be 5.0 - 0.6 =  4.4 volts at the drive, well below the design
> voltage. Use of a Schottky diode (0.34 volts) would help somewhat, but you
> have now narrowed the normal power design-margin by 90 percent, not good.
> 

Hardly a big deal since most logic is 3.3V these days (remember, you
don't need to maintain VccIO since the bus is dead anyway).

	-hpa
-- 
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