[mythtv-users] mythbackend hanging with busy disk

Håkon Alstadheim hakon at alstadheim.priv.no
Sat Apr 9 13:41:33 UTC 2016


Den 09. april 2016 15:05, skrev Jeffrey Ratcliffe:
> On 8 April 2016 at 22:00, Will Dormann <wdormann at gmail.com> wrote:
>> The SMART global results are worthless.  It'll almost always say
>> "PASSED".  Please post the entire results of smartctl -a
>
> $ sudo smartctl -a /dev/sda
> smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.13.0-85-generic] (local build)
> Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
>
> === START OF INFORMATION SECTION ===
> Model Family:     Western Digital Caviar Green (AF, SATA 6Gb/s)
> Device Model:     WDC WD20EARX-00PASB0
> Serial Number:    WD-WCAZAJ682312
> LU WWN Device Id: 5 0014ee 207994c3b
> Firmware Version: 51.0AB51
> User Capacity:    2,000,398,934,016 bytes [2.00 TB]
> Sector Sizes:     512 bytes logical, 4096 bytes physical
> Device is:        In smartctl database [for details use: -P show]
> ATA Version is:   ATA8-ACS (minor revision not indicated)
> SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
> Local Time is:    Sat Apr  9 15:04:14 2016 CEST
> 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:  (0x84)    Offline data collection activity
>                     was suspended 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:         (39900) seconds.
> Offline data collection
> capabilities:              (0x7b) SMART execute Offline immediate.
>                     Auto Offline data collection on/off support.
>                     Suspend Offline collection upon new
>                     command.
>                     Offline surface scan supported.
>                     Self-test supported.
>                     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:      ( 384) minutes.
> Conveyance self-test routine
> recommended polling time:      (   5) minutes.
> SCT capabilities:            (0x3035)    SCT Status supported.
>                     SCT Feature Control supported.
>                     SCT Data Table supported.
>
> 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     0x002f   200   200   051    Pre-fail
> Always       -       0
>   3 Spin_Up_Time            0x0027   175   171   021    Pre-fail
> Always       -       6250
>   4 Start_Stop_Count        0x0032   096   096   000    Old_age
> Always       -       4872
>   5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail
> Always       -       0
>   7 Seek_Error_Rate         0x002e   200   200   000    Old_age
> Always       -       0
>   9 Power_On_Hours          0x0032   091   091   000    Old_age
> Always       -       7145
>  10 Spin_Retry_Count        0x0032   100   100   000    Old_age
> Always       -       0
>  11 Calibration_Retry_Count 0x0032   100   100   000    Old_age
> Always       -       0
>  12 Power_Cycle_Count       0x0032   096   096   000    Old_age
> Always       -       4872
> 192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age
> Always       -       47
> 193 Load_Cycle_Count        0x0032   114   114   000    Old_age
> Always       -       258165
> 194 Temperature_Celsius     0x0022   118   107   000    Old_age
> Always       -       32
> 196 Reallocated_Event_Count 0x0032   200   200   000    Old_age
> Always       -       0
> 197 Current_Pending_Sector  0x0032   200   200   000    Old_age
> Always       -       0
> 198 Offline_Uncorrectable   0x0030   200   200   000    Old_age
> Offline      -       0
> 199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age
> Always       -       0
> 200 Multi_Zone_Error_Rate   0x0008   200   200   000    Old_age
> Offline      -       0
>
> SMART Error Log Version: 1
> No Errors Logged
>
> SMART Self-test log structure revision number 1
> No self-tests have been logged.  [To run self-tests, use: smartctl -t]
>
>
> 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.
>

I notice it is a "green" drive. At least until your issues are fixed,
you might look into how to make the drive NOT go to sleep. I had a green
drive once that gave me some of grief as a mythtv storage drive,
recordings would fail because the drive did not wake up fast enough.

I'd say the smart output looks good, except that no self-test has run to
completion. Try running extended self test while not using the drive for
anything. You have to leave it for  11 hours and 5 minutes (that is
39900 seconds). If the drive is in use, the time for the test is a lot
longer. If not using the drive and/or keeping the machine running is
impossible, look into running successive selective self-tests until the
whole drive has been tested.

Side-note: I have a couple of seagate nas drives that seem incapable of
completing the extended self-test. Turns out to  be a known issue. Never
heard of that for WD though.

If your data is not life-or-death you could look into making the drive
error out early (rather than re-trying for a long time) on reads that
fail. Something like smartctl -l scterc,70,70 . This setting is normally
only used for raid members.

If you have an almost-but-not-completely failing read somewhere on the
drive, no sectors will be marked bad until you WRITE to the failing
sector, or until a self-test reaches that sector. Even if you have
sectors marked bad those sectors will not be re-mapped until you write
to that sector.



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