Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion

[Edward Shishkin <edward@namesys.com>]

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.

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