From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hans Reiser <reiser@namesys.com>
Subject: Re: the " 'official' point of view" expressed by kernelnewbies.org
 regarding reiser4 inclusion
Date: Thu, 03 Aug 2006 11:26:55 -0600
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To: Edward Shishkin <edward@namesys.com>
Cc: Matthias Andree <matthias.andree@gmx.de>, ric@emc.com, Alan Cox <alan@lxorguk.ukuu.org.uk>, Adrian Ulrich <reiser4@blinkenlights.ch>, "Horst H. von Brand" <vonbrand@inf.utfsm.cl>, bernd-schubert@gmx.de, reiserfs-list@namesys.com, jbglaw@lug-owl.de, clay.barnes@gmail.com, rudy@edsons.demon.nl, ipso@snappymail.ca, lkml@lpbproductions.com, jeff@garzik.org, tytso@mit.edu, linux-kernel@vger.kernel.org

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?

>
>
>  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.
>
>