Question: Out of curiosity, I ran GNU ddrescue on a Seagate ST1000LM024 HN-M101MBB hard drive with known bad sectors, and then I visualized the ddrescue mapfile with ddrescueview.

When I zoomed in, this interesting pattern appeared:

The green gaps (contiguous good sectors) are often 2440 logical sectors (1249280 bytes) large, and the red sections (bad and probably physically damaged sectors) are almost always 1 physical sector (4 logical sectors, 4096 bytes) large.

Keeping this pattern in mind, I did a calculation to estimate how many sectors would be on the track. ?The hard drive spins at 5400 rotations per minute, the sustained read rate at that part of the drive is about 109 mebibytes per second (I tested this on a drive of the same model with no bad sectors), one track goes around 360 degrees, and a logical sector is 512 bytes.

((109MiB/s / 5400rpm * 360 degrees) / 512 bytes) = 2480

The estimation shows that there are about 2480 logical sectors in the affected track. ?The pattern happens every 2444 logical sectors.

This suggests that the physical damage looks like a very thin strip heading inwards practically tangent to the circle of the platter. ?The thin strip fits in an arc less than 0.001639 . ?This damage, whatever it is, appears to be a microscopic gash.

There are other characteristics of the pattern that I can’t quite make sense of.

The bad sectors only exist in the first ¹/₆ of the drive, the outer edges, with no clear pattern of where the bands of patterns appear.
The patterns don’t appear to be one long gash; they’re more like a dotted/dashed line (” “):

Why would damage appear like this? ?What could create such an orderly damage pattern?

Reference

S.M.A.R.T.

# smartctl -a /dev/sdfsmartctl 6.4 2014-10-07 r4002 [x86_64-linux-4.3.0-0.bpo.1-amd64] (local build)Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org=== START OF INFORMATION SECTION ===Model Family: ?Seagate Momentus SpinPoint M8 (AF)Device Model: ?ST1000LM024 HN-M101MBBSerial Number: ?S314J90G121745LU WWN Device Id: 5 0004cf 20f07d081Firmware Version: 2BA30003User Capacity: ?1,000,204,886,016 bytes [1.00 TB]Sector Sizes: ?512 bytes logical, 4096 bytes physicalRotation Rate: ?5400 rpmForm Factor: ?2.5 inchesDevice is: ?In smartctl database [for details use: -P show]ATA Version is: ?ATA8-ACS T13/1699-D revision 6SATA Version is: ?SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)Local Time is: ?Sat Mar 19 10:02:27 2016 CDTSMART support is: Available – device has SMART capability.SMART support is: Enabled=== START OF READ SMART DATA SECTION ===SMART overall-health self-assessment test result: PASSEDGeneral SMART Values:Offline data collection status: ?(0x00) Offline data collection activity ???was never started. ???Auto Offline Data Collection: Disabled.Self-test execution status: ?( 121) The previous self-test completed having ???the read element of the test failed.Total time to complete Offlinedata collection: ?(12480) seconds.Offline data collectioncapabilities: ??(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 routinerecommended polling time: ?( ?2) minutes.Extended self-test routinerecommended polling time: ?( 208) minutes.SCT capabilities: ?(0x003f) SCT Status supported. ???SCT Error Recovery Control supported. ???SCT Feature Control supported. ???SCT Data Table supported.SMART Attributes Data Structure revision number: 16Vendor Specific SMART Attributes with Thresholds:ID# ATTRIBUTE_NAME ?FLAG ?VALUE WORST THRESH TYPE ?UPDATED ?WHEN_FAILED RAW_VALUE ?1 Raw_Read_Error_Rate ?0x002f ?100 ?100 ?051 ?Pre-fail ?Always ?- ?118722 ?2 Throughput_Performance ?0x0026 ?252 ?252 ?000 ?Old_age ?Always ?- ?0 ?3 Spin_Up_Time ?0x0023 ?092 ?092 ?025 ?Pre-fail ?Always ?- ?2494 ?4 Start_Stop_Count ?0x0032 ?100 ?100 ?000 ?Old_age ?Always ?- ?96 ?5 Reallocated_Sector_Ct ?0x0033 ?252 ?252 ?010 ?Pre-fail ?Always ?- ?0 ?7 Seek_Error_Rate ?0x002e ?252 ?252 ?051 ?Old_age ?Always ?- ?0 ?8 Seek_Time_Performance ?0x0024 ?252 ?252 ?015 ?Old_age ?Offline ?- ?0 ?9 Power_On_Hours ?0x0032 ?100 ?100 ?000 ?Old_age ?Always ?- ?4188 10 Spin_Retry_Count ?0x0032 ?252 ?252 ?051 ?Old_age ?Always ?- ?0 11 Calibration_Retry_Count 0x0032 ?100 ?100 ?000 ?Old_age ?Always ?- ?21 12 Power_Cycle_Count ?0x0032 ?100 ?100 ?000 ?Old_age ?Always ?- ?102 13 Read_Soft_Error_Rate ?0x003a ?100 ?100 ?000 ?Old_age ?Always ?- ?0181 Program_Fail_Cnt_Total ?0x0022 ?100 ?100 ?000 ?Old_age ?Always ?- ?655675191 G-Sense_Error_Rate ?0x0022 ?100 ?100 ?000 ?Old_age ?Always ?- ?56192 Power-Off_Retract_Count 0x0022 ?100 ?100 ?000 ?Old_age ?Always ?- ?25193 Load_Cycle_Count ?0x0032 ?089 ?089 ?000 ?Old_age ?Always ?- ?111986194 Temperature_Celsius ?0x0002 ?058 ?050 ?000 ?Old_age ?Always ?- ?42 (Min/Max 14/50)195 Hardware_ECC_Recovered ?0x003a ?100 ?100 ?000 ?Old_age ?Always ?- ?0196 Reallocated_Event_Count 0x0032 ?252 ?252 ?000 ?Old_age ?Always ?- ?0197 Current_Pending_Sector ?0x0032 ?037 ?037 ?000 ?Old_age ?Always ?- ?10437198 Offline_Uncorrectable ?0x0030 ?252 ?252 ?000 ?Old_age ?Offline ?- ?0199 UDMA_CRC_Error_Count ?0x0036 ?200 ?200 ?000 ?Old_age ?Always ?- ?0200 Multi_Zone_Error_Rate ?0x002a ?100 ?100 ?000 ?Old_age ?Always ?- ?3688240 Head_Flying_Hours ?0x0032 ?100 ?100 ?000 ?Old_age ?Always ?- ?4186241 Total_LBAs_Written ?0x0032 ?097 ?094 ?000 ?Old_age ?Always ?- ?4770327242 Total_LBAs_Read ?0x0032 ?096 ?094 ?000 ?Old_age ?Always ?- ?5931956254 Free_Fall_Sensor ?0x0032 ?252 ?252 ?000 ?Old_age ?Always ?- ?0SMART Error Log Version: 1Warning: ATA error count 13458 inconsistent with error log pointer 4ATA Error Count: 13458 (device log contains only the most recent five errors) ?CR = Command Register [HEX] ?FR = Features Register [HEX] ?SC = Sector Count Register [HEX] ?SN = Sector Number Register [HEX] ?CL = Cylinder Low Register [HEX] ?CH = Cylinder High Register [HEX] ?DH = Device/Head Register [HEX] ?DC = Device Command Register [HEX] ?ER = Error register [HEX] ?ST = Status register [HEX]Powered_Up_Time is measured from power on, and printed asDDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,SS=sec, and sss=millisec. It “wraps” after 49.710 days.Error 13458 occurred at disk power-on lifetime: 4188 hours (174 days + 12 hours) ?When the command that caused the error occurred, the device was active or idle. ?After command completion occurred, registers were: ?ER ST SC SN CL CH DH ?– — — — — — — ?40 51 08 28 ec cb e2 ?Error: UNC 8 sectors at LBA = 0x02cbec28 = 46918696 ?Commands leading to the command that caused the error were: ?CR FR SC SN CL CH DH DC ?Powered_Up_Time ?Command/Feature_Name ?– — — — — — — — ?—————- ?——————– ?c8 00 08 28 ec cb e2 08 ?00:02:49.684 ?READ DMA ?b0 d5 01 00 4f c2 00 08 ?00:02:49.684 ?SMART READ LOG ?ef 10 02 00 00 00 a0 08 ?00:02:49.684 ?SET FEATURES [Enable SATA feature] ?27 00 00 00 00 00 e0 08 ?00:02:49.684 ?READ NATIVE MAX ADDRESS EXT [OBS-ACS-3] ?ec 00 00 00 00 00 a0 08 ?00:02:49.684 ?IDENTIFY DEVICEError 13457 occurred at disk power-on lifetime: 4188 hours (174 days + 12 hours) ?When the command that caused the error occurred, the device was active or idle. ?After command completion occurred, registers were: ?ER ST SC SN CL CH DH ?– — — — — — — ?40 51 08 28 ec cb e2 ?Error: UNC 8 sectors at LBA = 0x02cbec28 = 46918696 ?Commands leading to the command that caused the error were: ?CR FR SC SN CL CH DH DC ?Powered_Up_Time ?Command/Feature_Name ?– — — — — — — — ?—————- ?——————– ?c8 00 08 28 ec cb e2 08 ?00:02:49.681 ?READ DMA ?b0 da 00 00 4f c2 00 08 ?00:02:49.681 ?SMART RETURN STATUS ?ef 10 02 00 00 00 a0 08 ?00:02:49.681 ?SET FEATURES [Enable SATA feature] ?27 00 00 00 00 00 e0 08 ?00:02:49.681 ?READ NATIVE MAX ADDRESS EXT [OBS-ACS-3] ?ec 00 00 00 00 00 a0 08 ?00:02:49.681 ?IDENTIFY DEVICEError 13456 occurred at disk power-on lifetime: 4188 hours (174 days + 12 hours) ?When the command that caused the error occurred, the device was active or idle. ?After command completion occurred, registers were: ?ER ST SC SN CL CH DH ?– — — — — — — ?40 51 08 28 ec cb e2 ?Error: UNC 8 sectors at LBA = 0x02cbec28 = 46918696 ?Commands leading to the command that caused the error were: ?CR FR SC SN CL CH DH DC ?Powered_Up_Time ?Command/Feature_Name ?– — — — — — — — ?—————- ?——————– ?c8 00 08 28 ec cb e2 08 ?00:02:49.677 ?READ DMA ?b0 d1 01 01 4f c2 00 08 ?00:02:49.677 ?SMART READ ATTRIBUTE THRESHOLDS [OBS-4] ?ef 10 02 00 00 00 a0 08 ?00:02:49.677 ?SET FEATURES [Enable SATA feature] ?27 00 00 00 00 00 e0 08 ?00:02:49.677 ?READ NATIVE MAX ADDRESS EXT [OBS-ACS-3] ?ec 00 00 00 00 00 a0 08 ?00:02:49.677 ?IDENTIFY DEVICEError 13455 occurred at disk power-on lifetime: 4188 hours (174 days + 12 hours) ?When the command that caused the error occurred, the device was active or idle. ?After command completion occurred, registers were: ?ER ST SC SN CL CH DH ?– — — — — — — ?40 51 08 28 ec cb e2 ?Error: UNC 8 sectors at LBA = 0x02cbec28 = 46918696 ?Commands leading to the command that caused the error were: ?CR FR SC SN CL CH DH DC ?Powered_Up_Time ?Command/Feature_Name ?– — — — — — — — ?—————- ?——————– ?c8 00 08 28 ec cb e2 08 ?00:02:49.674 ?READ DMA ?b0 d0 01 00 4f c2 00 08 ?00:02:49.674 ?SMART READ DATA ?ef 10 02 00 00 00 a0 08 ?00:02:49.674 ?SET FEATURES [Enable SATA feature] ?27 00 00 00 00 00 e0 08 ?00:02:49.674 ?READ NATIVE MAX ADDRESS EXT [OBS-ACS-3] ?ec 00 00 00 00 00 a0 08 ?00:02:49.674 ?IDENTIFY DEVICEError 13454 occurred at disk power-on lifetime: 4188 hours (174 days + 12 hours) ?When the command that caused the error occurred, the device was active or idle. ?After command completion occurred, registers were: ?ER ST SC SN CL CH DH ?– — — — — — — ?40 51 08 28 ec cb e2 ?Error: UNC 8 sectors at LBA = 0x02cbec28 = 46918696 ?Commands leading to the command that caused the error were: ?CR FR SC SN CL CH DH DC ?Powered_Up_Time ?Command/Feature_Name ?– — — — — — — — ?—————- ?——————– ?c8 00 08 28 ec cb e2 08 ?00:02:49.670 ?READ DMA ?ec 00 01 00 00 00 00 08 ?00:02:49.670 ?IDENTIFY DEVICE ?ef 10 02 00 00 00 a0 08 ?00:02:49.670 ?SET FEATURES [Enable SATA feature] ?27 00 00 00 00 00 e0 08 ?00:02:49.670 ?READ NATIVE MAX ADDRESS EXT [OBS-ACS-3] ?ec 00 00 00 00 00 a0 08 ?00:02:49.670 ?IDENTIFY DEVICESMART Self-test log structure revision number 1Num ?Test_Description ?Status ??Remaining ?LifeTime(hours) ?LBA_of_first_error# 1 ?Short offline ?Completed: read failure ?90% ?4101 ?933752# 2 ?Short offline ?Completed: read failure ?90% ?4101 ?933752# 3 ?Short offline ?Completed: read failure ?90% ?4101 ?1417744# 4 ?Short offline ?Completed without error ?00% ?3607 ?-# 5 ?Short offline ?Completed without error ?00% ?3002 ?-# 6 ?Short offline ?Completed without error ?00% ?2338 ?-# 7 ?Short offline ?Completed without error ?00% ?1044 ?-# 8 ?Short offline ?Completed without error ?00% ?334 ?-# 9 ?Short offline ?Completed without error ?00% ?0 ?-SMART Selective self-test log data structure revision number 0Note: revision number not 1 implies that no selective self-test has ever been run SPAN ?MIN_LBA ?MAX_LBA ?CURRENT_TEST_STATUS ?1 ?0 ?0 ?Completed_read_failure [90% left] (0-65535) ?2 ?0 ?0 ?Not_testing ?3 ?0 ?0 ?Not_testing ?4 ?0 ?0 ?Not_testing ?5 ?0 ?0 ?Not_testingSelective 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.

What causes this HDD sector damage pattern?

Reference

S.M.A.R.T.

ddrescue mapfile

ddrescueview Gallery

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