Re: scary ext2 filesystem question

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sat, 26 Dec 1998 19:50:15 +0000 (GMT)


> Isn't it that Linux may write data before writing metadata, so it could
> write the data, but it doesn't show up in the (on-disk) file? As a result,
> FFS might give you a file with garbage (allocated blocks that were never
> written to), Linux might give you a short file (or loose it completely). Is
> that correct?

FFS gives you garbage, ext2fs gives you a file where the last few updates
were lost.

> If the above is true, it looks like both are roughly equally vulnerable,
> but I'd prefer the Linux failure mode.

With FFS you are more likely to get corrupt but apparently correct files,
and on some versions are highly likely to end up with blocks attached
to the file that were never 'cleaned' from their previous usage.

With ex2ts thats still possible but its more likely you end up with a slightly
shorter file where recent updates were lost

Alan

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