Re: READ CAPACITY 16

[Matthew Wilcox <matthew@wil.cx>]

On Wed, Dec 17, 2008 at 02:14:09PM -0500, James Bottomley wrote:
> On Wed, 2008-12-17 at 12:11 -0700, Matthew Wilcox wrote:
> > On Wed, Dec 17, 2008 at 02:04:52PM -0500, James Bottomley wrote:
> > > Actually, we can't afford to send READ CAPACITY(16) to failing devices;
> > > some of them never come back.
> > 
> > When you say 'never come back', do you mean:
> > 
> > a) The drive discards the command silently
> > b) The drive hangs until a reset is issued
> > c) The drive hangs until it's power-cycled
> > d) The drive turns into a paperweight
> 
> All of the above ... this is USB ... well, I don't *know* of a D
> case ... but I wouldn't bet one doesn't exist.

The unfortunate thing is that we don't have a collection of INQUIRY
results from these devices, so we can't say whether checking for SCSI_2
would eliminate those in categories C and D.

Are you willing to take a patch that sends RC16 for devices claiming
SCSI_2, and falls back to RC10 if that doesn't work?  Or shall I try to
implement algorithm D and talk to T10?

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."