Blue wrote:
>> Now, regarding the "insane" -S4 setting for laptop mode: this setting is
>> intended for battery mode only,
> 	
> 	 But it gets activated for desktop where battery status cannot be
> determined,too. And this is bad.

ACK, definitely.

> Also, I don't find smart to try to
> bring down the disk every 20 seconds because it is very likely that you
> will have to respin it very, very soon later because of user activity or
> system activity (there are a lot of files that are open and appended at,
> varios logs, xsession-errors and so on). 

This is what laptop mode is for. It makes sure that writes _do not_ get 
sent to disk too often. Otherwise, you will get spindowns every 30 
seconds because of atime updates. I routinely get multiple-minute 
spindowns. However, it shouldn't be used when you're not on battery. And 
then the disk shouldn't spin down, or even park its disk too often. The 
problem is that this does happen now, without the 
disk-activity-avoidance tweaks provided by laptop mode. Which is exactly 
when the -S4 setting is _not_ applied. So any criticism of the -S4 
setting is not relevant to this bug report at all.

> I'm not sure that we should bring the power management to  extreme.
> Please set -S4 to your laptop and let it idle. You will see that anyway\
 > the hard disk stops and respins every 1..2 minutes.

If you don't enable laptop mode, yes, then this happens. That's why -S4 
should only be enabled in combination with laptop mode.

>> Anyway, I think that any power management settings which make a drive
>> load/unload once every minute *all the time* are doomed to kill drives.
>> No need to blame this problem on the -S4, which is for a very special
>> use case (on battery) only.
> 
>      Anyway, it seems that we have actually more problems. It is the
> Load/Unload period -which we should address by putting a hdparm -B with
> an appropriate value, and the spindown timeout which we should address
> so that it really makes sense and does not creates a situation where
> even let idle the system will get spinned/downspinned every minute or
> two. If someone really needs that kind of power saving then he/she
> should consider solid state disks which are more appropriate for
> economy.

My concern is that you seem to couple the -B value with the -S4 value 
here. The -S4 setting is only applied by laptop-mode-tools when two 
conditions are met: (a) laptop mode is enabled (which is not the case by 
default), and (b) the laptop is on battery (which is not mentioned 
anywhere in this bug report as being a condition of the problem 
occurring). AFAICT this bug report concerns the -B value, not the -S 
value. The -S4 value is very sensible when laptop mode is enabled. I 
wouldn't want you people starting to fiddle with it to fix this bug 
report when it, in fact, won't help, and will only throw away the baby 
with the bath water for laptop mode users. If you go and tweak the way 
-B settings are applied, be my guest. It seems to be the proper fix for 
this bug. But PLEASE don't mix it up with this setting, which isn't even 
applied in the situations that this bug report is about.

> The third problem would be that on systems where the battery status
> cannot be determined, to NOT activate extreme power management schemes,
> because the system could be a desktop (with a drive not appropriate for
> extreme power management) or a server...

Definitely a problem. If Ubuntu only used the AC detection logic built 
into the upstream laptop-mode-tools package, which does work like that...

> And finally, I am still not convinced that a spin/unspin every minute or
> to is healthy on ANY drive. A definitive answer regarding how sane would
> be each of the settings (for load/unload and spin/unspin) could only be
> given by a manufacturer representative. And while I myself do not have
> the strings to require (and get) an official answer, Canonical on the
> other hand, as a big commercial entity could be able to get it so that
> once and forever we can set some settings at boot that are safe
> according to the manufacturer's guidelines. 
> Actually,  I think that  this would be the best (and first) step to be
> taken by the Canonical/Ubuntu team should do to address an issue that is
> getting fuzzier and more debated by the day.

I think the typical drive specs could be a very good start in this 
respect, even without the connections of a company like Canonical. The 
reference number of 600000 is a very nice aim. IMHO the question to 
drive manufacturers shouldn't be whether it is good to spin down drives 
more than they are specced for (it isn't), or whether it's OK to spin 
them down once a minute (it's OK as long as you stay within the specced 
limits). As far as I'm concerned, the big question is: which -B settings 
correspond to how many spindowns, so what would be a safe on-AC setting? 
My best guess for now is 254...