I've got a 1Tb USB disc that appears to be dying - eg it took about 10 days (!) to run 'badblocks -nsv /dev/sdc' and it only did less than 2% in that time. Read access became _really_ slow. So there's definitely something amiss and I've got it offline. There's no drama about the content as I have other backups and I'm resigned to junking the thing, but I'm curious about the fact that smartctl doesn't seem to report any errors. I tried a short and a long test but nothing in there seems to be alarming - in fact it says PASSED!! - but the output is pretty opaque and maybe I've been foxed by ambiguity. Anyone care to comment on it? Here it is: [root at nina bhepple]# smartctl /dev/sdc -a smartctl 5.43 2012-06-30 r3573 [i686-linux-2.6.32-358.23.2.el6.i686] (local build) Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net === START OF INFORMATION SECTION === Model Family: Western Digital Caviar Green Device Model: WDC WD10EAVS-00M4B0 Serial Number: WD-WCAV5A574187 LU WWN Device Id: 5 0014ee 2aef3c352 Firmware Version: 01.00A01 User Capacity: 1,000,204,886,016 bytes [1.00 TB] Sector Size: 512 bytes logical/physical Device is: In smartctl database [for details use: -P show] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Mon Jan 27 17:43:33 2014 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: (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: (18780) 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: ( 217) minutes. Conveyance self-test routine recommended polling time: ( 5) minutes. SCT capabilities: (0x3037) 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 114 107 021 Pre-fail Always - 7283 4 Start_Stop_Count 0x0032 091 091 000 Old_age Always - 9764 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 080 080 000 Old_age Always - 14907 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 100 100 000 Old_age Always - 181 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 82 193 Load_Cycle_Count 0x0032 186 186 000 Old_age Always - 44531 194 Temperature_Celsius 0x0022 098 083 000 Old_age Always - 49 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 192 192 000 Old_age Always - 1423 198 Offline_Uncorrectable 0x0030 196 196 000 Old_age Offline - 700 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 001 001 000 Old_age Offline - 793265 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 Extended offline Completed: read failure 90% 14545 1141581559 # 2 Short offline Completed: read failure 90% 14545 1141577005 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.