Re: scary ext2 filesystem question

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sat, 26 Dec 1998 02:54:21 +0000 (GMT)

> Try a DejaNews search. This comes up fairly often in Linux vs BSD
> flamewars. It appears to me that the situation is as follows:
>
> 1. The Berkeley system is theoretically better than ext2 from a data
> integrety point of view, and ext2 is better from a performance point
> of view.
>
> 2. In practice, ext2 is extremely robust. It doesn't lose data nearly as
> often as one would theoretically expect it to. In fact, it loses data
> about as often as the theoretically much superior FFS loses data (e.g.,
> both get hosed so infrequently as to make a comparision impossible).

Please don't continue to perpetrate this urban myth. The BSD FFS is more likely
to be corrupt than the ext2fs (note that their new journalling softupdate stuff
deals with most of the BSD ffs problems)

Standard BSD writes metadata synchronously. This means it writes the size
and block lists before the data. On a crash and fsck you get files that are
correct to fsck (the block info is right) but whose data was never written.

On Linux you may also not get the file itself if it was just created. fsck has
to be a little smarter but there is no difference on a data integrity issue.

Alan

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