Re: document ext3 requirements

Pavel Machek
2009-01-05T09:38:30Z

> >Sector writes are atomic (ATOMIC-SECTORS)
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >Either whole sector is correctly written or nothing is written during
> >powerfail.
> >
> > Unfortuantely, none of the cheap USB/SD flash cards I seen do
> > behave like this, and are unsuitable for all linux filesystems
> > I know.
> >
> > An inherent problem with using flash as a normal block
> > device is that the flash erase size is bigger than
> > most filesystem sector sizes. So when you request a
> > write, it may erase and rewrite the next 64k, 128k, or
> > even a couple megabytes on the really _big_ ones.
> >
> > If you lose power in the middle of that, filesystem
> > won't notice that data in the "sectors" _after_ the
> > one your were trying to write to got trashed.
>
> around, not after. the block you are reading could be in the middle or at
> the end of an eraseblock.

Applied, thanks.

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