Re: Blockbusting news, results get worse

[Pavel Machek]

Hi!

> > >> 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:
> 
> http://marc.theaimsgroup.com/?l=linux-kernel&m=100665153518652&w=2

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...

								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/