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

[Endolith]

I'm seeing about 0.5 load cycles per hour now, so this is no longer a
problem for me using acpi-support 0.114-0intrepid1 from Proposed.  It's
too late for my current hard drive (1,351,794 load cycles), but at least
I won't have to worry about the replacement dying young, too. :)  Thank
you!

** Description changed:

  This is not a support forum.  Please do not use it as such (even though
  it has been used as such already).
  
  You can scan through the bug for links to the Ubuntu forums where many,
  many different questions have been asked, answered, and re-answered.
  The temporary workaround is just below.
  
  See https://wiki.ubuntu.com/PowerManagement for an overview about what
  is involved and for a remedy.
  
  SRU justification: current behavior may lead to premature disk failure
  in laptops due to excessive unnecessary drive parking.  Fix will disable
  disk cycling by default when on AC power, by correcting an error in the
  hdparm logic of acpi-support.
  
  For jaunty, this issue is addressed in acpi-support 0.115.
  
  TEST CASE:
  
  1. With acpi-support 0.109 (hardy) or 0.114 (intrepid) installed and laptop-mode *not* enabled in either /etc/default/laptop-mode or /etc/default/acpi-support, monitor the load cycle count of your hard drive by running 'sudo smartctl -a /dev/sda|grep Load_Cycle_Count' over an interval of several minutes, and observe that it is incrementing.  (If it does not increment, your hard drive's manufacturer defaults are sane and you are not affected by this problem.)
  2. install acpi-support from hardy-proposed or intrepid-proposed
  3. while connected to AC power, monitor 'sudo smartctl -a /dev/sda|grep Load_Cycle_Count' again to confirm that the number is no longer incrementing
  4. (assuming that the system is a laptop:) disconnect the system from AC power, and confirm that the number is incrementing again
  5. enable laptop mode by setting ENABLE_LAPTOP_MODE=true in /etc/default/laptop-mode and running 'sudo /etc/init.d/laptop-mode restart'
  6. reconnect the system to AC power and confirm that the Load_Cycle_Count stops incrementing.
  7. suspend and resume the system and confirm that the Load_Cycle_Count is still not incrementing.
  
  REGRESSION POTENTIAL:
  
  As this patch causes "hdparm -B 128" and "hdparm -B 254" to be invoked
  automatically on systems where it was not being run before, there is
  some risk that this change will have a measurable impact on the disk
  throughput, power consumption, and temperature of some hard drives.
  Nevertheless, it is believed that these APM power settings are the
  sensible default settings for the vast majority of hard drives and that
  the current behavior poses a significant risk to the longevity of hard
  drives used in a wide range of laptop models, so this update should only
  be blocked if it results in confirmed hardware damage that can be
  expected to apply to a similar range of configurations.
  
  Following is a summary of the issue:
  It is confirmed that some systems are seeing an unusually high number of load/unload cycles on their hard disks, as evidenced by smartctl.
  
  It was originally surmised that this was related to laptop-mode being
  enabled, but this especially affects systems where laptop-mode is
  disabled.  In fact, aggressive APM is not a bad idea while a system is
  not on AC, as that system is much more likely to encounter a physical
  impact.
  
  This is due to disk APM settings that let the heads park or disk spin
  down after an idle period that is shorter than the regular disk access
  patterns of the OS.
  
  Then, the heads are only parked for a very short period of time and
  almost imediately loaded again. Making impact protection much
  ineffective and wearing out the drive.
  
  It can happen when the disk asumes aggressive APM settings (like many
  laptop disks) and the OS does not take care to set the APM settings
  accordingly to its current disk access pattern.
  
  This problem has been confirmed in Ubuntu as well as in other
  distributions and on MacOS X and Windows.
  
  Symptoms of this bug are:
  * Frequent HD clicks  -- more than one per 3 minutes while idle, louder than the typical access sounds.  Often more than twice per minute.  On some disks, the click is very quiet
  * Rapidly Increasing Load_Cycle_Count as displayed in the final number in "sudo smartctl -a /dev/hda | grep Load_Cycle_Count" (where /dev/hda is replaced with your own hard disk device)
  
  The problem is only present due to the existence of *all four* of the following factors:
  * Hardware is set (default or otherwise) to aggressive power management, causing heads to park.  (default behaviour of many drives and often the only user available type of power management)
  * Disk is touched often, causing heads to unpark. (default behaviour of many distributions)
  * Drives are spec'd to a limited number of these cycles.  (600,000 is the most common, although some may be spec'd higher or lower).
  * The OS not setting disk APM variables according to current disk access pattern.
  
  Reasonable Limits / Criteria for a fix:
  * There should be fewer than ~15 load cycles per hour, except during heavy usage while on battery.
  * This provides a life expectancy of over four years, which is reasonable for a hard disk.
  
  Temporary Workaround:
  * Follow the above link.
  
  Some hardware with this issue:
  WD1200VE -- http://www.wdc.com/en/library/portable/2879-001121.pdf -- This aggressive parking is a feature of this disk, but that feature relies on behaviour that allows for significant amounts of (truly) idle time without the disk being touched. Notice the "Load/unload cycles" of 600,000.
  
  Example Load_Cycle_Counts: 
  * Thinkpad Z60m/Hitachi HTS541080G9SA00 with well over 7000 load cycles in only 100 hours.  That's >70 per hour.
  * Gateway MT6451/Western Digital WD1200VE with 164762 load cycles in 3747 hours (156 days) of uptime.  That's ~43 per hour -- except that the system was patched during the initial third of its life, which puts it at ~63/hour since Gutsy was installed (and wasn't patched, as I had done with feisty).
+ * Dell Inspiron 8600/Hitachi HTS721010G9AT00 with 200 to 280 load cycles per hour
  
  Please see for yourself how often your drive is load cycling:
  smartctl -d ata -a /dev/sda
  (This command is for an SATA drive; you'll need to install the smartmontools package first.)
  
  You can get the average per hour by the following division:
  Load_Cycle_Count / Power_On_Hours
  
  Old workaround for 7.10 (not working in 8.04):   https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695/comments/14
  A more extensive description of the workaround: http://ubuntuforums.org/showthread.php?t=591503
  
  You may need to use '254', or a bit lower, as opposed to '255'.  If HD temperature gets high, you may want to set it all the way "down" to 200 or so.  ~1 click every 2.5-3 minutes is fine.
  Note:  Some disks are unresponsive to having their APM changed by hdparm, and therefore the workaround doesn't work.  It would be a good idea, in such cases, to disable APM in the BIOS if possible.
  
  See also http://paul.luon.net/journal/hacking/BrokenHDDs.html for a
  rather dramatic account of the effects the current default values may
  have.

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