Don't confuse head parking with spindown! [LWN.net]

Don't confuse head parking with spindown!

Posted Nov 17, 2007 11:22 UTC (Sat) by anton (subscriber, #25547)
Parent article: Laptops, power management, and Ubuntu

The article and many comments confuse head parking with spindown:

The hard disk spindle is spun down to save power (or on switching the machine off) and is counted by the SMART Start_Stop_Count counter (ID 4). You can control the spindown timeout with hdparm -S; on many drives you can also spin down immediately with hdparm -y.
Head parking without spinning down is done by laptop drives to make the drive more resilient to shock, and is counted by the SMART Load_Cycle_Count counter. Head parking alone does not save power. You can control it on many drives with hdparm -B (which may also have other effects). The heads are also parked when the drive spins down.

The issue that caused the recent headlines is the head parking. That issue is not new. It was already old news when I first encountered it in 2005.

BTW, given that the hard drive manufacturers fail to provide a standard interface to control head parking (and the APM feature (hdparm -B) does not help on some drives), I don't see how anybody but the hard drive manufacturers can be blamed for parking the head too often. E.g., my WDC WD400UE-22HCT0 parked the heads every 30s without caring for disk activity (the spindown timeout is smarter); fortunately, hdparm -B 254 helped.

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Don't confuse head parking with spindown!

Posted Dec 16, 2007 12:45 UTC (Sun) by PaulD (guest, #49571) [Link]

Hello everyone,

This is my first post here. I just wanted to put in my "two cents worth".

Firstly, thanks for all your advice and information. I appreciate it and I have been
experienced similar "problems" on my ageing but reliable Toshiba Satellite M-30 whilst running
Ubuntu. I can't understand until this is sorted out why you guys want to risk your hardware?
It's just not worth it... unless you have heaps of money to burn that is... In my mind it's
not worth even discussing it until these bugs are worked out. I'm not gonna be anyone's guinea
pig thanks.

I just wanted to relay my thoughts...

A. I'm not pointing the finger but in the case of Ubuntu, the current revision is 7.010 right?
This problem has been happening for ages so why is it not sorted out by now? Sure the OS has
(apparently) +made many advances BUT why not get the mechanics right FIRST instead of
concentrating on giving us a pretty GUI?

All we have are tons of dubious suggestions, hacks, vague technical explanations, and lets
face it "guesses" as to how to fix this problem which have frankly left me extremely
frustrated and which I do not understand because the hype promised me that I didn't have to be
technically minded to operate Ubuntu. I also don't undertand why some people continue to point
the finger at hardware manufacturers? You see, a sticker on my laptop clearly reads "designed
for Windows XP". It doesn't say "designed for Linux". Despite being almost three years ago
this old laptop can do anything I throw it and runs XP just as well as any of the new laptops
my frends have. It's been my main computer, not just a laptop, for all this time, switched on
night and day most of the time 24-hours and I cannot break it so why should I want to let
Linux break it for me?

Despite this I listened to the hype and recently excitedly installed Ubuntu (dual boot with
XP). From the start I got immediately suspicious of this crazy overzealous hard-drive
activity. All of my Toshiba Power saving stuff was turned off. Made no difference whatsoever.
I searched the forums for weeks. I looked for Linux utilities to help. I thought logically
someone might have written a reliable utility to fix this or at least help. Nope, apparently
not.

The net effect: I'm not prepared to risk my hardware (yes it's old - I can't afford to buy a
new one at the moment) until the OS is working properly). And why should I, it's a fantastic
machine.

Ubuntu comes with a power-saving utility but why on earth does it not include a sliding-scale
option to change CPU power (up or down)like the Toshiba Power Saver does. This shouldn't be
too hard. This opens up another issue. Over heating. You see the hotter your CPU runs the
more your laptop is gonna heat up. I run my laptop at 70% with not a single problem in all
these years. Who the heck cares if I have to wait two milliseconds more here and there if Im'
gonna potentially get another year or two of life outta my machine! It's still damned fast.
With Ubuntu it heats up significantly more than under XP. So... run the CPU slower, keep
everything cool. thats the key. BUT I still cant find a decent, reliable Linux utility to do
this for me either.

Im not willing to destroy my CPU or my hard disk on the basis of any OS that is very immature
(despite the hype) and doesn't have manufacturer support and also does not have it where it
counts. Core functionality and reliability is the key. This is where XP win hands down.

Also I thought users didn't have to be technically inclined to use Ubunutu? Every forum I've
seen everything suggestions entail going straight to the commands like an entering cryptic
commands and switches. Uggghhh... Users like me don't understand this jargon (but again
according to the hype we don't need to!) and it only pushes us away from using Ubuntu. Stick
with XP, it's still a million miles in front. Yes, you have to pay for it, yes it has issues,
but at the end of the day, it works. It's polished. It's professional (more than Linux OS's
anyway) and it won't destroy your hardware. One day when someone works out the bugs I will
look towards with great anticipation to trying a Linux disto again but not for a while. For
now, I'm sticking with XP because I trust it.