Re: Race to power off harming SATA SSDs

From	Pavel Machek <pavel@ucw.cz>
Newsgroups	linux.kernel
Subject	Re: Race to power off harming SATA SSDs
Date	2017-05-08 13:00 +0200
Message-ID	<tEOyt-2Rv-7@gated-at.bofh.it> (permalink)
References	(1 earlier) <tuRnX-7Fz-5@gated-at.bofh.it> <tECnD-34t-21@gated-at.bofh.it> <tELhf-SA-1@gated-at.bofh.it> <tEN9o-24v-19@gated-at.bofh.it> <tENj4-28p-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon 2017-05-08 10:34:08, David Woodhouse wrote:
> On Mon, 2017-05-08 at 11:28 +0200, Pavel Machek wrote:
> > 
> > Are you sure you have it right in JFFS2? Do you journal block erases?
> > Apparently, that was pretty much non-issue on older flashes.
> 
> It isn't necessary in JFFS2. It is a *purely* log-structured file
> system (which is why it doesn't scale well past the 1GiB or so that we
> made it handle for OLPC).
> 
> So we don't erase a block until all its contents are obsolete. And if
> we fail to complete the erase... well the contents are either going to
> fail a CRC check, or... still be obsoleted by later entries elsewhere.
> 
> And even if it *looks* like an erase has completed and the block is all
> 0xFF, we erase it again and write a 'clean marker' to it to indicate
> that the erase was completed successfully. Because otherwise it can't
> be trusted.

Aha, nice, so it looks like ubifs is a step back here.

'clean marker' is a good idea... empty pages have plenty of space.

How do you handle the issue during regular write? Always ignore last
successfully written block?

Do you handle "paired pages" problem on MLC?

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Thread

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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