[Bug 913050] Re: Explicit APM values in hdparm-functions cause Load Cycle Count hell

[Daniel Swarbrick]

My SAMSUNG HM251JJ also suffers this problem.

If hdparm sets -B128, it sticks:

sudo hdparm -B128 /dev/sda

/dev/sda:
 setting Advanced Power Management level to 0x80 (128)
 APM_level	= 128

And as per the hdparm manpage, it does not spin down. Ever.

But if it sets -B127, the hard disk assumes a value of 1:

sudo hdparm -B127 /dev/sda

/dev/sda:
 setting Advanced Power Management level to 0x7f (127)
 APM_level	= 1

And it starts to spin down a lot more than it should, sometimes even
during disk reads!

hdparm -i shows:

/dev/sda:

 Model=SAMSUNG HM251JJ, FwRev=2AA00_00, SerialNo=xxxx
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
 RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
 BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=488397168
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4 
 DMA modes:  mdma0 mdma1 mdma2 
 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 
 AdvancedPM=yes: disabled (255) WriteCache=enabled
 Drive conforms to: ATA/ATAPI-7 T13 1532D revision 0:  ATA/ATAPI-1,2,3,4,5,6,7

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https://bugs.launchpad.net/bugs/913050

Title:
  Explicit APM values in hdparm-functions cause Load Cycle Count hell

Status in “hdparm” package in Ubuntu:
  Confirmed

Bug description:
  Release: 12.04 (development) maybe 11.10 is affected too?
  Hard drive:
  Model Family:     Seagate Momentus 5400.6
  Device Model:     ST9250315AS

  In recent hdparm version explicit APM values are set in /lib/hdparm
  /hdparm-functions. "On AC" value = 254, "on battery value" = 127. This
  causes load cycle hell on my disk drive. Even 128 causes the same
  thing, so 11.10 seems to be affected too.

  Lines in question:

  hdparm_options()
  {
      local WANTED_DISK="$1"

      local DISC= DEFAULT= DEF_QUIET= COMMAND_LINE=
      # if the below is guaranteed to spawn a subshell, then this next line is
      # unnecessary
      local OPTIONS OPT_QUIET KEY SEP VALUE

      egrep -v '^[[:space:]]*(#|$)' /etc/hdparm.conf |
      {
          # set our default global apm policy here.
          if hdparm_try_apm "$WANTED_DISK"; then
              if hdparm_is_on_battery; then
                  hdparm_set_option -B127
              else
                  hdparm_set_option -B254
              fi
          fi

  There obviously must be some workarounds by setting right values in
  /etc/hdparm.conf but I can not elaborate any further.

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