lkml.org 
[lkml]   [2006]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: New filesystem for Linux
>> There was discussion about it here some times ago, and I think the result 
>> was that the IDE bus is reset prior to capacitors discharge and total loss
>> of power and disk has enough time to finish a sector --- but if you have
>> crap power supply (doesn't signal power loss), crap motherboard (doesn't
>> reset bus) or crap disk (doesn't respond to reset), it can fail.
>
> Hmm, maybe. But I think I saw couple of such bad sectors that were only bad
> because of power loss in the wild.
>
>
>> BTW. reiserfs and xfs depend on this feature too. ext3 is the only one that
>> doesn't.
>
> Well, at least for XFS everybody tell that it should be used with UPS only if
> you really care about your data. I think it has something to do with heavy
> in-RAM caching this filesystem does.

System is allowed to cache anything unless sync/fsync is called. Someone
told that XFS has some bugs that if crashed incorrectly, it can lose
already synced data ... don't know. Plus it has that infamous feature (not
a bug) that it commits size-increase but not data and you see zero-filed
files.

> Anyway, it looks strange to list something very fragile and potentially not
> existing in the requirements... :-)

Better to list it than quitly depend on it like ext2/fat/reiser/xfs/
(maybe jfs?) do.

> Could you explain where exactly do you depend on this requirement? And what
> could happen if it is not true?

If you write a file in a directory and the sector is unwritable upon write
& crash, you lose those few files near it. Just the similar way you would
lose 4 files in inode table on ext2 in this case.

> Thanks,
>
> Grzegorz Kulewski
>
>
> PS. Do you have any benchmarks of your filesystem? Did you do any longer
> automated tests to prove it is not going to loose data to easily?

I have, I may find them and post them. (but the university wants me to
post them to some conference, so I should keep them secret :-/)

Mikulas

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-03 02:37    [W:0.120 / U:0.540 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site