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Message-ID: <69304d110608041157p125e5c8oef58b02f6c81fa29@mail.gmail.com>
Date: Fri, 4 Aug 2006 20:57:46 +0200
From: "Antonio Vargas" <windenntw@...il.com>
To: "Edward Shishkin" <edward@...esys.com>
Cc: "Hans Reiser" <reiser@...esys.com>,
"Matthias Andree" <matthias.andree@....de>, ric@....com,
"Alan Cox" <alan@...rguk.ukuu.org.uk>,
"Adrian Ulrich" <reiser4@...nkenlights.ch>,
"Horst H. von Brand" <vonbrand@....utfsm.cl>,
bernd-schubert@....de, reiserfs-list@...esys.com,
jbglaw@...-owl.de, clay.barnes@...il.com, rudy@...ons.demon.nl,
ipso@...ppymail.ca, lkml@...productions.com, jeff@...zik.org,
tytso@....edu, linux-kernel@...r.kernel.org
Subject: Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion
On 8/4/06, Edward Shishkin <edward@...esys.com> wrote:
> Hans Reiser wrote:
> > Edward Shishkin wrote:
> >
> >
> >>Matthias Andree wrote:
> >>
> >>
> >>>On Tue, 01 Aug 2006, Hans Reiser wrote:
> >>>
> >>>
> >>>
> >>>>You will want to try our compression plugin, it has an ecc for every
> >>>>64k....
> >>>
> >>>
> >>>
> >>>What kind of forward error correction would that be,
> >>
> >>
> >>
> >>Actually we use checksums, not ECC. If checksum is wrong, then run
> >>fsck - it will remove the whole disk cluster, that represent 64K of
> >>data.
> >
> >
> > How about we switch to ecc, which would help with bit rot not sector loss?
>
> Interesting aspect.
>
> Yes, we can implement ECC as a special crypto transform that inflates
> data. As I mentioned earlier, it is possible via translation of key
> offsets with scale factor > 1.
>
> Of course, it is better then nothing, but anyway meta-data remains
> ecc-unprotected, and, hence, robustness is not increased..
>
> Edward.
>
> >
> >>
> >> and how much and
> >>
> >>
> >>>what failure patterns can it correct? URL suffices.
> >>>
> >>
> >>Checksum is checked before unsafe decompression (when trying to
> >>decompress incorrect data can lead to fatal things). It can be
> >>broken because of many reasons. The main one is tree corruption
> >>(for example, when disk cluster became incomplete - ECC can not
> >>help here). Perhaps such checksumming is also useful for other
> >>things, I didnt classify the patterns..
> >>
> >>Edward.
> >>
> >>
Would the storage + plugin subsystem support storing >1 copies of the
metadata tree?
--
Greetz, Antonio Vargas aka winden of network
http://network.amigascne.org/
windNOenSPAMntw@...il.com
thesameasabove@...gascne.org
Every day, every year
you have to work
you have to study
you have to scene.
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