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Re: Race to power off harming SATA SSDs

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On Mon, 8 May 2017, David Woodhouse wrote:

> > I've got a problem with the underlying mechanism. How long does it take to 
> > erase a NAND block? A couple of milliseconds. That means that for an erase 
> > to be "weak" du to a power fail, the host CPU must issue an erase command, 
> > and then the power to the NAND must drop within those milliseconds. 
> > However, in most systems there will be a power monitor which will 
> > essentially reset the CPU as soon as the power starts dropping. So in 
> > practice, by the time the voltage is too low to successfully supply the 
> > NAND chip, the CPU has already been reset, hence, no reset command will 
> > have been given by the time NAND runs out of steam.
> > 
> > Sure, with switchmode power supplies, we don't have those large capacitors 
> > in the power supply which can keep the power going for a second or more, 
> > but still, I would think that the power wouldn't die fast enough for this 
> > to be an issue.
> > 
> Our empirical testing trumps your "can never happen" theory :)

I'm sure it does. But what is the explanation then? Has anyone analyzed 
what is going on using an oscilloscope to verify relationship between 
erase command and supply voltage drop?

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30

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Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 00:00 +0200
  Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 09:30 +0200
    Re: Race to power off harming SATA SSDs Ricard Wanderlof <ricard.wanderlof@axis.com> - 2017-05-08 09:40 +0200
      Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 10:20 +0200
        Re: Race to power off harming SATA SSDs Ricard Wanderlof <ricard.wanderlof@axis.com> - 2017-05-08 10:40 +0200
          Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 11:00 +0200
            Re: Race to power off harming SATA SSDs Ricard Wanderlof <ricard.wanderlof@axis.com> - 2017-05-08 11:10 +0200
              Re: Race to power off harming SATA SSDs Hans de Goede <hdegoede@redhat.com> - 2017-05-08 11:10 +0200
                Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 12:20 +0200
                Re: Race to power off harming SATA SSDs Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-05-08 14:00 +0200
                Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 17:50 +0200
                Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 23:40 +0200
                Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 18:50 +0200
                Re: Race to power off harming SATA SSDs Tejun Heo <tj@kernel.org> - 2017-05-08 19:50 +0200
                Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 21:00 +0200
                Re: Race to power off harming SATA SSDs Tejun Heo <tj@kernel.org> - 2017-05-08 21:10 +0200
                RE: Race to power off harming SATA SSDs Atlant Schmidt <aschmidt@dekaresearch.com> - 2017-05-08 20:50 +0200
              Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 12:20 +0200
    Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 11:30 +0200
      Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 11:40 +0200
        Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 13:00 +0200
          Re: Race to power off harming SATA SSDs Richard Weinberger <richard.weinberger@gmail.com> - 2017-05-08 13:10 +0200
            Re: Race to power off harming SATA SSDs Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-05-08 14:00 +0200
            Re: Race to power off harming SATA SSDs Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-05-08 14:00 +0200
              Re: Race to power off harming SATA SSDs Richard Weinberger <richard@nod.at> - 2017-05-08 14:20 +0200
          Re: Race to power off harming SATA SSDs David Woodhouse <dwmw2@infradead.org> - 2017-05-08 13:20 +0200
            Re: Race to power off harming SATA SSDs Pavel Machek <pavel@ucw.cz> - 2017-05-08 14:40 +0200
      Re: Race to power off harming SATA SSDs Richard Weinberger <richard.weinberger@gmail.com> - 2017-05-08 12:00 +0200

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