Re: PMP SMART error recovery and failure code decoding help

[Marc MERLIN <marc@merlins.org>]

On Mon, Jan 17, 2011 at 06:12:09PM +0100, Tejun Heo wrote:
> Hello,
> 
> On Mon, Jan 17, 2011 at 08:43:40AM -0800, Marc MERLIN wrote:
> > > It could be that the drives need to spin up to answer the smart
> > > command and the timeout on the smart commands is a bit too short for
> > > that to happen.  Forcing a disk access before issuing the smart
> > > command could work around the problem.
> >  
> > Right, although the idea is of course to keep the drives spun down :)
> > I haven't been able to find which SMART call is causing those errors yet.
> > Does cmd b0/d8:00:00:4f:c2/00:00:00:00:00/00 translate to anything useful?
> 
> That's SMART ENABLE OPERATIONS.  It turns on SMART.
 
Haha, ok, not as useful as I thought :)

> > > > That said, is it normal/expected for the PMP code to do a full bus reset
> > > > because of a SMART command that couldn't go through?
> > > 
> > > Yeah, after a timeout, the driver doesn't know what state the
> > > controller / PMP / devices are in, so it's kind of forced to do full
> > > reset.
> > 
> > Fair enough. I guess it's one of the downsides of PMP.
> 
> The device would still be reset even if it's attached directly.  The
> only different is that everything under PMP is reset together instead
> of individual ones.

That's absolutely correct. I was kind of trying to avoid unnecessary full
PMP resets: they always make me nervous with software raid on top, but so
far no real disasters have happened :)

Thanks for your answers,
Marc
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