Re: reiser4 plugins

Grzegorz Kulewski
2005-06-26T17:39:16Z

On Sun, 26 Jun 2005, Alan Cox wrote:

> On Gwe, 2005-06-24 at 20:21, Hans Reiser wrote:
>> Alan, this is FUD. Our V3 fsck was written after everything else was,
>> for lack of staffing reasons (why write an fsck before you have an FS
>> worth using). As a result, there was a long period where the fsck code
>> was unstable. It is reliable now.
>>
>> People often think that our tree makes fsck less robust. Actually fsck
>> can throw the entire internal tree away and rebuild from leaf nodes, and
>> frankly that makes things pretty robust.
>
> I did a series of tests well after resier3 had fsck that consisted of
> modelling the behaviour of systems under error state. I modelled random
> bit errors, bit errors at a fixed offset (class ram failure), sector 4
> byte slip (known IDE fail case) and sectors going away.
>
> Reiserfs didn't handle it anything like as gracefully as ext2. Its a
> pretty easy experiment to write the code for and the results are
> interesting.

Maybe but I once checked some other error scenario. I generated (by
mistake of course) dm table that lineary connected 3 times the same
partition (instead of 3 different partitions). Both Reiser4 and Reiserfs3
gave a lot of errors while trying to use such device. Ext3 did not give
single error and was hapily droping my data,

I agree that this is not very useful test case for disk problems but it
shows that, at least, checks for trouble in Reiser4 are miles before those
in Ext2/3. If only Reiser4 could print a note what I done wrong... ;-)

Grzegorz Kulewski