Re: XFS corruption during power-blackout

[Jens Axboe <axboe@suse.de>]

On Fri, Jul 01 2005, Bryan Henderson wrote:
> >>But how does the end-user know what hardware is "good hardware"? Which
> >>vendors don't lie (or, at least, lie less than others) regarding HDs?
> >>
> >
> >The only real way is to test the drive (and retest when you get a new 
> >versions of firmware) and the whole fsync -> write barrier code path.
> 
> Wouldn't a commercial class drive that ignores explicit flushes be 
> infamous?  I'm ready to accept that there are SCSI drives that cache 
> writes in volatile storage by default (but frankly, I'm still skeptical), 
> but I'm not ready to accept that there are drives out there secretly 
> ignoring explicit commands to harden data, thus jeopardizing millions of 
> dollars' worth of data.  I'd need more evidence.

I'm pretty sure I have an IBM drive that does so (its flush cache
command is _really_ fast), as a matter of fact :-) I need to locate it
and put it in a test box to re-ensure this.

I'm not sure such drives would necessarily be infamous, hardly anyone
would notice anything wrong in a desktop type machine. Which is what
these drives were made for.

-- 
Jens Axboe