Re: Corruption Stats (fwd)

Rob Hagopian (hagopiar@vuser.vu.union.edu)
Thu, 30 Jul 1998 00:15:47 -0400 (EDT)


It's not true though, Apple had a BIG problem with this at one point -
they started shipping computers with the write cache enabled on the
internal drives (and it was about time). Of course, the Macs all have
software power-off (<ob Macs rule> ;-) and the file system would get
corrupted. IIRC, the solution was simply to delay long enough for the
caches to flush automaticly.
-Rob H.

On Wed, 29 Jul 1998, Linus Torvalds wrote:

> On Thu, 30 Jul 1998, Stefan Traby wrote:
> >
> > BTW: A drive following the SCSI-specs may cause disk-corruption
> > under Linux (WCE=1). Data may still be in write-cache after
> > shutdown and power-off. (I miss "synchronize cache").
> > This is for shure a theoretical problem, but a practical bug.
> > Or did I miss something ?
>
> No, you didn't miss anything.
>
> The thing has been discussed occasionally (very occasionally), and I don't
> know what the proper response is. According to some people the better
> drives make sure that they have enough rotational energy that they can
> make sure they get their data written out even after powerdown, but
> personally that sounds like science fiction to me (oh, I wouldn't be
> surprised if there are some drives that do it, but I'd be surprised if
> it's universal).
>
> Of course, Linux itself won't ever shut off the power, so it's more a
> matter of "when can you safely say 'System halted.'" than anything else.
> The kernel does support some shutdown features, but the disk is not on
> that list.
>
> Linus

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