2.5インチHDDのLoad_Cycle_Countの上昇

S.M.A.R.T. の中で Load_Cycle_Count というのがあり、WD GREEN に属する HDD では、IntelliPark という機能の作用で、このカウンタがどんどん上がるという話題が有名です。
WD GREEN に限った性質と思ってましたが、ふと手持ちの 2.5 インチ HDD の値を見てみたら、結構な値になっていました。調べてみると、どうやら、APM 機能によるもののようです。

[root@hoge ~]# smartctl -g apm /dev/sdc
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-642.3.1.el6.x86_64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

APM level is:     128 (minimum power consumption without standby)
[root@hoge ~]# smartctl -s apm,253 /dev/sdc
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-642.3.1.el6.x86_64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

APM set to level 253 (intermediate level without standby)
[root@hoge ~]# smartctl -A /dev/sdc
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-642.3.1.el6.x86_64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF READ SMART DATA SECTION ===
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   100   100   062    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   100   100   040    Pre-fail  Offline      -       0
  3 Spin_Up_Time            0x0007   173   173   033    Pre-fail  Always       -       2
  4 Start_Stop_Count        0x0012   099   099   000    Old_age   Always       -       1873
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   100   100   040    Pre-fail  Offline      -       0
  9 Power_On_Hours          0x0012   093   093   000    Old_age   Always       -       3451
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       1716
191 G-Sense_Error_Rate      0x000a   100   100   000    Old_age   Always       -       0
192 Power-Off_Retract_Count 0x0032   097   097   000    Old_age   Always       -       393906
193 Load_Cycle_Count        0x0012   097   097   000    Old_age   Always       -       37845
194 Temperature_Celsius     0x0002   166   166   000    Old_age   Always       -       36 (Min/Max 7/53)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0022   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0008   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x000a   200   200   000    Old_age   Always       -       259
223 Load_Retry_Count        0x000a   100   100   000    Old_age   Always       -       0

[root@hoge ~]# smartctl -A /dev/sdc
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-642.3.1.el6.x86_64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF READ SMART DATA SECTION ===
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   100   100   062    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   100   100   040    Pre-fail  Offline      -       0
  3 Spin_Up_Time            0x0007   173   173   033    Pre-fail  Always       -       2
  4 Start_Stop_Count        0x0012   099   099   000    Old_age   Always       -       1873
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   100   100   040    Pre-fail  Offline      -       0
  9 Power_On_Hours          0x0012   093   093   000    Old_age   Always       -       3452
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       1716
191 G-Sense_Error_Rate      0x000a   100   100   000    Old_age   Always       -       0
192 Power-Off_Retract_Count 0x0032   097   097   000    Old_age   Always       -       393906
193 Load_Cycle_Count        0x0012   097   097   000    Old_age   Always       -       37845
194 Temperature_Celsius     0x0002   162   162   000    Old_age   Always       -       37 (Min/Max 7/53)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0022   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0008   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x000a   200   200   000    Old_age   Always       -       259
223 Load_Retry_Count        0x000a   100   100   000    Old_age   Always       -       0

APM 設定を 253 にすると上がらなくなりました。ただし、温度が高めになります。254 が maximum performance なのですが、254 だと更に温度が高くなるようで、253 のほうが良好に感じました。