shutdown -r / shutdown -h / reboot all hang and don't cleanly dismount

[Jeremy Chadwick]

On Wed, Jun 19, 2013 at 11:34:39AM -0500, Matthew D. Fuller wrote:
> On Wed, Jun 19, 2013 at 09:16:35AM -0700 I heard the voice of
> Jeremy Chadwick, and lo! it spake thus:
> > 
> > The above CDB + subcommand disables APM entirely.  There is a lot
> > more to APM than just parking heads (and in all honesty, APM should
> > have nothing to do with parking heads).  Disabling APM can actually
> > have drastic effects on drive temperature (meaning there are certain
> > chip and/or motor operations that said feature controls *in
> > addition* to head parking), and other firmware-level features that
> > aren't documented.
> 
> True enough, in concept.  With all the drives sitting behind
> ventilation perfectly capable of dealing with 15kRPM drives, I don't
> worry about what that might do to the 7200's though...

Justified in your environment, but not in mine -- where most of my
systems (at home) are extremely quiet (1000-1200rpm fans, lots of noise
dampening material, etc.).  A 10C increase *during idle* is enough to
make me wary.  I also have extremely sensitive hearing, so drives
clicking is something I can hear from quite a distance -- I guess
working with them for so long over the years has made me sensitive to
'em.

> > Furthermore, that CDB does not work for all drives.  There are
> > Seagate drives -- I know because I bought some and returned them
> > when the APM trick did not work -- that lack the LCC-disable tie-in
> > to APM.  The drive either rejected the CDB (ATA status code error
> > returned), while others accepted it but nothing in 0xec (IDENTIFY)
> > reported as got changed.
> 
> Well, I haven't seen it with these.  Several of
> ada0: <ST1000DM003-9YN162 CC4D> ATA-8 SATA 3.x device
> and some systems with CC4C too.

The drives I was testing were STx000DM001.  I don't remember if I had a
DM002.  I also don't remember the firmware version they had on them, but
I do remember there were no updates available from Seagate at that time.
On the other hand, their forum was *filled* with post after post about
the issue, including one fellow whose drive in something like 3 months
was almost reaching MTBF head park/reload count.

But my point is this: 3.5" drives do not need this feature in 95% of
environments.  In desktop systems it's worthless -- in consumer desktops
it accomplishes nothing but noise and annoyance and impacts I/O, and in
business desktop desktop environments it serves no purpose because most
places have their desktops go into sleep mode (so drive standby/sleep
gets used).  And in the server environment it's pure 100% worthless.

With 2.5" drives I can see it being more useful, but only if the drive
is used in a laptop.  There are NASes (and now servers too!) which use
2.5" drives, and I sure as hell wouldn't want that happening there.

So really it's just a bad feature all around that should be specific to
one environment demographic; the vendors should have made a 2.5" drive
"dedicated for laptops" that had this feature enabled, while disabld on
all other drives (2.5" and 3.5").  What we got was nearly opposite.

> > I will have -- and eat -- their souls.
> 
> The problem with that is that the undigestible bits of "soul" just get
> passed right back into the ecosystem, and in a more concentrated form.
> 
> Some might suggest that's already happened, and is got us here in the
> first place  8-}

If you had what I do (moderate-to-severe IBS), you'd know that it
definitely doesn't get passed back in a more concentrated form.  First
joke I've been able to make about my health condition, yeah!  Ha!  I
kill me! -- Alf

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |