[Bug 59695] Re: High frequency of load/unload cycles on some hard disks may shorten lifetime

[Dennis Noordsij]

Just to (re?)state the obvious:

A standard Linux kernel flushes to disk every 5 seconds. I don't know
what anyone expects their disk to do to "save power" between those
flushes, but it doesn't. When the drive manufacturer sets default
settings it is under the assumption the OS is not going to force the
disk up every 5 seconds, but rather is going to make an effort to
minimize disk access. If the OS knows it needs the disk every 5 seconds,
it should explicitly disable APM.

Ubuntu is "at fault" (and I don't mean this offensively!) in that it
allows APM to be enabled but does not enable the laptop_mode of the
kernel to minimize disk access.

Sure the drive/BIOS default settings are aggressive, sure the disk wants
to park after 1 second and spin down after 2 - this would be fine if
Ubuntu would minimize disk access, but ANY power saving settings is
unacceptable with a standard install which kicks the disk every 5
seconds. Exactly how should it save power that way ?

Without laptop-mode enabled and active there should be no APM enabled at
all.


Similarly, for the following and similar quotes:

"So the ball is in the manufacturer's court in that they need to adjust
the head parking idle time to something more sensible, or at least
provide utilities that can allow the user to tweak the setting. Hitachi
for one does not provide this ability."

Linux is forcing the disk up unconditionally every 5 seconds - there is
no "sensible setting" for head parking idle time except "off"!

What am I missing that seems to make this such a complicated issue ?
When not in laptop_mode, APM must be off. Period. Nothing to do with
firmare or BIOS. Nothing to do with settings. Just common sense. If you
kick the disk every 5 seconds, APM makes no sense. What is the disk
going to do to save power?

-- 
High frequency of load/unload cycles on some hard disks may shorten lifetime
https://bugs.launchpad.net/bugs/59695
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