LinuxQuestions.org - hdparm / APM / Hard Drive Clicking Sound

SHORT VERSION

Anyone know where I could find some documentation explaining the -B option of hdparm and it's implications regarding hard disk shock resistance and wear and tear? Or perhaps you have an explanation of your own? The man page is quite limited. =/

LONG VERSION

I recently noticed a clicking sound coming from my laptop's (Ubuntu 7.04) hard drive every few seconds. Google showed me I was far from being alone - seems tons of GNU/Linux users have encountered this problem. It also seems to be a pretty dangerous thing, as AFAICT it eats away at the hard disk's life. FWIW, it's a confirmed issue in Ubuntu's bug thing (I assume on other distros too):

https://bugs.launchpad.net/ubuntu/+bug/104535

https://bugs.launchpad.net/ubuntu/+s...ort/+bug/59695

A smartctl showed me my Load_Cycle_Count was through the roof. So I got worried about my drive dying a horrible early death and decided to work around the problem with what seems to be the most often recommended approach:

Code:

sudo hdparm -B 255 /dev/sda

The workaround worked fine - the clicking stopped (I also added the command to the startup sequence, etc). Granted, I can't change the past and whatever damage was done is done. I'm just happy I caught this sooner rather than later (the laptop is still relatively new).

Code:

win32sux@candystore:~$ sudo smartctl -a -d ata /dev/sda

smartctl version 5.36 [i686-pc-linux-gnu] Copyright (C) 2002-6 Bruce Allen

Home page is http://smartmontools.sourceforge.net/



=== START OF INFORMATION SECTION ===

Device Model:    Hitachi HTS541680J9SA00

Serial Number:    SBXXXXXXXXXXXXX

Firmware Version: SB2OC74P

User Capacity:    80,026,361,856 bytes

Device is:        Not in smartctl database [for details use: -P showall]

ATA Version is:  7

ATA Standard is:  ATA/ATAPI-7 T13 1532D revision 1

Local Time is:    Mon Oct  1 22:16:52 2007 EST

SMART support is: Available - device has SMART capability.

SMART support is: Enabled



=== START OF READ SMART DATA SECTION ===

SMART overall-health self-assessment test result: PASSED



General SMART Values:

Offline data collection status:  (0x85) Offline data collection activity

                                        was aborted by an interrupting command from host.

                                        Auto Offline Data Collection: Enabled.

Self-test execution status:      (  0) The previous self-test routine completed

                                        without error or no self-test has ever 

                                        been run.

Total time to complete Offline 

data collection:                ( 645) seconds.

Offline data collection

capabilities:                    (0x5b) SMART execute Offline immediate.

                                        Auto Offline data collection on/off support.

                                        Suspend Offline collection upon new

                                        command.

                                        Offline surface scan supported.

                                        Self-test supported.

                                        No Conveyance Self-test supported.

                                        Selective Self-test supported.

SMART capabilities:            (0x0003) Saves SMART data before entering

                                        power-saving mode.

                                        Supports SMART auto save timer.

Error logging capability:        (0x01) Error logging supported.

                                        General Purpose Logging supported.

Short self-test routine 

recommended polling time:        (  2) minutes.

Extended self-test routine

recommended polling time:        (  44) minutes.



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  0x0004  100  100  000    Old_age  Offline      -      1351

  3 Spin_Up_Time            0x0007  253  253  033    Pre-fail  Always      -      0

  4 Start_Stop_Count        0x0012  100  100  000    Old_age  Always      -      591

  5 Reallocated_Sector_Ct  0x0033  100  100  005    Pre-fail  Always      -      0

  7 Seek_Error_Rate        0x000a  100  100  000    Old_age  Always      -      0

  8 Seek_Time_Performance  0x0004  100  100  000    Old_age  Offline      -      0

  9 Power_On_Hours          0x0012  099  099  000    Old_age  Always      -      704

 10 Spin_Retry_Count        0x0012  100  100  000    Old_age  Always      -      0

 12 Power_Cycle_Count      0x0032  100  100  000    Old_age  Always      -      591

191 G-Sense_Error_Rate      0x000a  100  100  000    Old_age  Always      -      65536

192 Power-Off_Retract_Count 0x0032  099  099  000    Old_age  Always      -      259

193 Load_Cycle_Count        0x0012  093  093  000    Old_age  Always      -      79353

194 Temperature_Celsius    0x0002  144  144  000    Old_age  Always      -      38 (Lifetime Min/Max 22/48)

196 Reallocated_Event_Count 0x0032  100  100  000    Old_age  Always      -      1

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  253  000    Old_age  Always      -      0

223 Load_Retry_Count        0x000a  100  100  000    Old_age  Always      -      0

225 Load_Cycle_Count        0x0012  093  093  000    Old_age  Always      -      79353



SMART Error Log Version: 1

No Errors Logged



SMART Self-test log structure revision number 1

Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error

# 1  Short offline      Completed without error      00%        1        -

# 2  Short offline      Completed without error      00%        0        -



SMART Selective self-test log data structure revision number 1

 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS

    1        0        0  Not_testing

    2        0        0  Not_testing

    3        0        0  Not_testing

    4        0        0  Not_testing

    5        0        0  Not_testing

Selective self-test flags (0x0):

  After scanning selected spans, do NOT read-scan remainder of disk.

If Selective self-test is pending on power-up, resume after 0 minute delay.

So here's my questions: From what I've read, the clicking problem is due to excessive amounts of "disk head parking" going on. From what I understand, disk head parking is a safety measure which prevents damage to the drive when it's dropped, etc. For some reason, however, there is insane amounts of it happening out-of-the-box on some GNU/Linux setups. So what does this have to do with the disk's APM? From "man hdparm":

Code:

      -B    Set Advanced Power Management feature, if the drive supports it. A low value means aggressive power management and a high value means  bet‐

              ter performance. A value of 255 will disable apm on the drive.

Does this mean my drive was spinning down every few seconds? Or is the parking a separate thing which doesn't require spinning down? I actually thought that by not enabling "laptop mode" I wouldn't have any spin downs.

Code:

win32sux@candystore:~$ cat /proc/sys/vm/laptop_mode

0

I know that the 255 disables the APM feature, but I would like to know where can I find documentation about the other 254 possible settings? The man page's "aggressive" description doesn't say much. For example, if I would set 254, how exactly does that affect the drive? Is there a time calculation that needs to be done, as with other settings? I've tried googling for ATA power management specifications but didn't have any luck. Basically, I'm worried that by completely disabling this APM I have increased the risk of my disk being damaged if my laptop is dropped or something like that. Any light you can shed on this would be - as always - greatly appreciated.