Comment 252 for bug 59695

Mark,

Although I agree with some points you make, I want to question some
other assumptions.

Mark Thomas wrote:
> Disabling the APM feature of a drive can never be a fix. Parking the
> drives is a feature of the disk, and the The Load_Cycle_Count is
> supposed to go up, albeit slowly, during normal usage. The point of
> this bug is that the pathological worst case for load cycling is one
> access every 30 seconds or so, and Ubuntu is doing this by default.

I question the assumption that it needs to go up. I've had drives go
without load cycles for years, no problem. There are reasons for
parking: safety, and perhaps power usage (although that's fringe). IMHO
this means that it only strictly _needs_ to be on while on battery. As
ubuntu_demon pointed out earlier, leaving the APM setting at 128 while
on battery is probably mostly safe hard-drive-wear-wise, and has a
function. It is much harder to argue that APM needs to be enabled while
not on battery (i.e., not on the road).

> It is not the place for the operating system to save the user from
> themselves. You are correct in that the user could write a program that
> was detrimental to their hardware, but that is their choice.

I didn't mean to say that only programmers would have this problem, the
only reason I wanted to show a simple, seemingly harmless program was to
demonstrate that _any_ program that a user could install and run could
cause problems, without any clear sign that there would be anything
wrong with the situation.

What I mean to say is that *everybody* who runs *any* normal, bug-free
program on their computer now needs to be aware what the consequences
may be. Ubuntu is supposedly a distribution for people who don't have to
know these kinds of things. You're thinking of blaming my grandma if she
installs a third-party app, say, Skype (with some help from her
grandson) and then fails to check if it's an idle-writer? Be my guest!
But don't expect me to still consider installing Ubuntu on my grandma's
laptop. :-)

> We can't stop them from hitting their laptop with
> a hammer, either. Incidentally, it would be more likely to survive this
> if the hard drive heads were parked, and disabling APM will disable
> that.

Mostly useful in battery mode though. The next version of the workaround
in Debian's acpi-support package will set APM to 128 in battery mode and
to 254 on AC, to get the advantages of head parking (safety) on battery
while stopping the parking wear while plugged in.

> Furthermore, it has been shown that disabling APM can cause some drives
> to over-heat, so they will be definitely damaged if you do that, and by
> putting extra load on the battery you will be reducing its operational
> lifespan, too.

All I've seen is some 3-degree increases in temperature. I understand
that people might worry, but can you point me to where's the evidence of
actual overheating?

> Rolling out the workaround on every system, including those not
> currently affected, is a mistake. You will make the experience worse
> for some people (e.g. me. I have fixed all my idle-writers manually - my
> disk sleeps like a baby now), and you will make it possible for people
> to get lazy and ignore the problem, so it will never be fixed properly.
>
> A better short-term workaround would be to monitor the disks, and bring
> up a pop-up bubble offering to disable APM if the LCC is increasing too
> fast. I believe someone already suggested this.

If there's a failsafe way to detect the issue and only apply the
workaround in those cases, that would be fine by me. As long as it's
done, and as long as it's not just fixing idle-writers. Fixing
idle-writers can *never* solve this entire problem.

Cheers,
Bart