Spin down HDD after disk sync or before power off

[Daniel Thiele]

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Nate Eldredge wrote:
| On Thu, 5 Mar 2009, Tobias Blersch wrote:
|
|> Oliver Fromme wrote:
|>> > Joerg Sonnenberger wrote:
|>> > This is not true. Many hard disks don't like having to do an emergency
|>> > shutdown as it affects the disk life time negatively. That's what
|>> > happens if you poweroff the machine when the disks are still spinning.
|>>
|>> Can you point to any authoritative information (URL) about
|>> that claim, such as vendor specs, white paper or similar?
|>
|>
http://www.hitachigst.com/tech/techlib.nsf/techdocs/28DCCB17E0EEC5A086256F4E006E2F5B

|>
|>
|> Thats the specification for my notebooks hard drive. Section 6.6
|> Reliability gives data about how to power-off the disk. It also contains
|> numbers of supported load/unloads and emergency unloads. Emergency
|> unloads are invoked when the heads are still loaded and power fails.
|
| Ok, I didn't know that.  There are some drives that can unload the heads
| normally on power loss and don't need any special handling, and I was
| under the mistaken impression that this was universal.
|
| But the documentation suggests that this should be a BIOS function.
| When the kernel tries to poweroff the system, isn't that normally done
| via the BIOS (perhaps with ACPI/APM)?  So maybe the BIOS is supposed to
| unload the heads (by sending a standby/sleep command) before cutting the
| power.
|

Interestingly, the specification for the Hitachi drive in my notebook (a
TravelStar 5K320)

"Travelstar 5K320 Specification - HTSxxx models v1.0" avilable at
http://www.hitachigst.com/tech/techlib.nsf/products/Travelstar_5K320

says in the paragraph "Required power-off sequence": "The required host
system sequence for removing power from the drive is as follows [...]"
whereas the TravelStar 5K100 specifications lists exactly the same steps
but states that it is the BIOS' job to take care of executing them.

| Perhaps the OP's BIOS for some reason doesn't do this correctly.

I tried this on 2 different notebooks (2 ThinkPads though) and on both
machines the disks make a very audible "click" sound when I "shutdown -p
now" FreeBSD (6.x - CURRENT). With the patch I mentioned in my other
reply, however, the disks seem to power-off more smoothly. On a Samsung
X20 notebook I observed a comparable behavior.
So I am not sure if it is just one badly implemented function in very
few number of BIOSes or something that the operating system is supposed
to take care of or should at least try to. Just for comparison: The
original Windows XP on the Samsung X20 powers-off the disk in a "smooth"
way, too. Unfortunately, I haven't had the time to test this with other
operating systems.

Best regards,

Daniel
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