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 j...@koitsu.org | | UNIX Systems Administrator http://jdc.koitsu.org/ | | Making life hard for others since 1977. PGP 4BD6C0CB | _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
