On Thu, Nov 12, 2015 at 11:30:00AM +0100, Milan Broz wrote:
> Yes, please, patches do not to be production ready (I can integrate
> it to veritysetup upstream myself)
I'm working on this and should have a patch for veritysetup for you next
week.
Sami
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On Thu, Nov 12, 2015 at 01:50:04PM -0500, Mikulas Patocka wrote:
> What flash controller and chips do you use?
Considering the number of different devices running Android, I don't
have a good answer for this. I'm guessing most of them.
> Is the silent data corruption permanent or transient?
Most
On Wed, Dec 02, 2015 at 03:22:03PM -0500, Mike Snitzer wrote:
> Any progress on v2 that takes into account previous review feedback?
Yes. Sorry for the delay, the changes have gone through a couple of rounds
of internal reviews and testing first.
> Note I've staged the first 2 patches in this ser
On Mon, Nov 09 2015 at 2:19P -0500,
Sami Tolvanen wrote:
> On Mon, Nov 09, 2015 at 11:37:35AM -0500, Mike Snitzer wrote:
> > I'm left wondering: can the new error correction code be made an
> > optional feature that is off by default? -- so as to preserve some
> > isolation of this new code from
On Mon, 9 Nov 2015, Sami Tolvanen wrote:
> > Also, the 2 other big questions from Mikulas need answering:
> > 1) why aren't you actually adjustng error codes, returning success, if
> >dm-verity was able to trap/correct the corruption?
>
> We don't see actual I/O errors very often. Most corr
On 11/09/2015 08:19 PM, Sami Tolvanen wrote:
...
> We don't see actual I/O errors very often. Most corruption we've seen
> is caused by flaky hardware that doesn't return errors. However, I can
> certainly change to code to attempt recovery in this case too.
So if I understand it correctly, there
On Mon, Nov 09 2015 at 2:19pm -0500,
Sami Tolvanen wrote:
> On Mon, Nov 09, 2015 at 11:37:35AM -0500, Mike Snitzer wrote:
> > I'm left wondering: can the new error correction code be made an
> > optional feature that is off by default? -- so as to preserve some
> > isolation of this new code fro
On Mon, Nov 09, 2015 at 11:37:35AM -0500, Mike Snitzer wrote:
> I'm left wondering: can the new error correction code be made an
> optional feature that is off by default? -- so as to preserve some
> isolation of this new code from the old dm-verity behaviour.
It's optional in the sense that you m
On Thu, Nov 05 2015 at 12:33pm -0500,
Sami Tolvanen wrote:
> On Thu, Nov 05, 2015 at 08:34:04AM +0100, Milan Broz wrote:
> > could you please elaborate why is all this needed? To extend support
> > of some faulty flash chips?
>
> This makes dm-verity more robust against corruption caused by eith
On 2015-11-07 10:18, Mikulas Patocka wrote:
On Fri, 6 Nov 2015, Sami Tolvanen wrote:
On Fri, Nov 06, 2015 at 12:23:29PM -0500, Mikulas Patocka wrote:
Do you have some real case where such error corrections
increase longevity of some device?
Yes, there have been several cases where read-onl
On Fri, 6 Nov 2015, Sami Tolvanen wrote:
> On Fri, Nov 06, 2015 at 10:05:24PM +0100, Zdenek Kabelac wrote:
> > So how do you want to correctly 'restore' missing full sectors
> > with just 0.8% data overhead ??
>
> We use interleaving. Each byte in a 4k block is part of a different
> Reed-Solom
On Fri, 6 Nov 2015, Sami Tolvanen wrote:
> On Fri, Nov 06, 2015 at 08:20:15PM +0100, Zdenek Kabelac wrote:
> > i.e. you have 1G of space - you want to give 250MB as 'redundancy' -
> > so create 4 partition
>
> We cannot afford to set aside 25% of read-only partition space for
You can have
On Fri, 6 Nov 2015, Sami Tolvanen wrote:
> On Fri, Nov 06, 2015 at 12:23:29PM -0500, Mikulas Patocka wrote:
> > I'm also wondering what is this patch useful for. Disks and flash
> > controllers have their own error detection and correction
>
> I think I addressed this earlier. Some storage dev
On Fri, Nov 06, 2015 at 10:05:24PM +0100, Zdenek Kabelac wrote:
> So how do you want to correctly 'restore' missing full sectors
> with just 0.8% data overhead ??
We use interleaving. Each byte in a 4k block is part of a different
Reed-Solomon block, which means an entire lost 4k data block looks
Dne 6.11.2015 v 21:27 Sami Tolvanen napsal(a):
On Fri, Nov 06, 2015 at 08:20:15PM +0100, Zdenek Kabelac wrote:
i.e. you have 1G of space - you want to give 250MB as 'redundancy' -
so create 4 partition
well data safety has it's price - user should choose what he prefers
- more games and v
On Fri, Nov 06, 2015 at 08:20:15PM +0100, Zdenek Kabelac wrote:
> i.e. you have 1G of space - you want to give 250MB as 'redundancy' -
> so create 4 partition
We cannot afford to set aside 25% of read-only partition space for
redundancy on mobile devices, and would rather not impact performanc
Dne 6.11.2015 v 20:06 Sami Tolvanen napsal(a):
On Fri, Nov 06, 2015 at 12:23:29PM -0500, Mikulas Patocka wrote:
I'm also wondering what is this patch useful for. Disks and flash
controllers have their own error detection and correction
I think I addressed this earlier. Some storage devices are
On Fri, Nov 06, 2015 at 12:23:29PM -0500, Mikulas Patocka wrote:
> I'm also wondering what is this patch useful for. Disks and flash
> controllers have their own error detection and correction
I think I addressed this earlier. Some storage devices are able to
correct bit flips, but don't have eno
On Thu, 5 Nov 2015, Milan Broz wrote:
> On 11/05/2015 03:02 AM, Sami Tolvanen wrote:
> > This patch set adds error correction support to dm-verity, which
> > makes it possible to recover from data corruption in exchange of
> > increased space overhead.
> >
> > The feature is implemented as part
On Thu, Nov 05, 2015 at 08:34:04AM +0100, Milan Broz wrote:
> could you please elaborate why is all this needed? To extend support
> of some faulty flash chips?
This makes dm-verity more robust against corruption caused by either
hardware or software bugs, both of which we have seen in the past on
On 11/05/2015 03:02 AM, Sami Tolvanen wrote:
> This patch set adds error correction support to dm-verity, which
> makes it possible to recover from data corruption in exchange of
> increased space overhead.
>
> The feature is implemented as part of dm-verity to take advantage
> of the existing has
This patch set adds error correction support to dm-verity, which
makes it possible to recover from data corruption in exchange of
increased space overhead.
The feature is implemented as part of dm-verity to take advantage
of the existing hash tree to improve performance and locate known
erasures.
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