Re: Blockbusting news, results get worse
From: Pavel Machek (pavel_at_ucw.cz)
Date: Wed, 29 Oct 2003 21:01:41 +0100 To: John Bradford <firstname.lastname@example.org>
> > >> or put it under heavy write workload and remove
> > >> power.
> > >>
> > > Can you tell us more about what really happens to disk drives when the
> > > power is cut while a block is being written? We engage in a lot of
> > > uninformed speculation, and it would be nice if someone who really knows
> > > told us....
> > >
> > > Do drives have enough capacitance under normal conditions to finish
> > > writing the block? Does ECC on the drive detect that the block was bad
> > > and so we don't need to detect it in the FS?
> > Does it really matter to speculate about this?
> > If you don't FLUSH CACHE, you have no guarantees your data is on the
> > platter.
> I think that the idea that is floating around is to deliberately ruin
> the formatting on part of the drive in order to simulate a bad block.
> Operation of disk drives immediately after a power failiure has been
> discussed before, by the way:
Well, that looks like pure speculation.
BTW I *do* believe that powerfail can make the sector bad. Imagine you
bump into bad sector during write, and need to reallocate...
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