Re: [Qemu-devel] Re: [PATCH][v2] Align file accesses with cache=off (O_DIRECT)

[Andreas Färber]

Am 21.05.2008 um 04:12 schrieb Anthony Liguori:

> Jamie Lokier wrote:
> > What do you imagine happens when you pull the power in the middle of
> > writing a sector to a floppy disk (to pick a more easily imagined
> > example)?
> >
> > There is not enough residual power to write the rest of the sector.
> > That sector's checksum will therefore be corrupt, and (hopefully)  
> > have
> > a CRC read error.  It can be written over again, wiping the CRC  
> > error.
>
> Why would the sector's checksum be corrupt?  The checksum wouldn't  
> change after the data write.

If you change part of the data but leave the checksum as-is, you'd  
hopefully get a checksum mismatch... ;)

Andreas