SMART Devices
Listing 11: Vendor-Specific Attributes
# /usr/local/sbin/smartctl -a /dev/sda smartctl 7.2 2020-07-11 r5076 [x86_64-linux-5.4.0-42-generic] (CircleCI) Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION === Model Family: Samsung based SSDs Device Model: Samsung SSD 840 Series Serial Number: S19HNSAD620520T LU WWN Device Id: 5 002538 5a0050931 Firmware Version: DXT08B0Q User Capacity: 120,034,123,776 bytes [120 GB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device TRIM Command: Available, deterministic, zeroed Device is: In smartctl database [for details use: -P show] ATA Version is: ACS-2, ATA8-ACS T13/1699-D revision 4c SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Sun Aug 2 10:57:50 2020 EDT 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: (0x80) Offline data collection activity was never started. Auto Offline Data Collection: Enabled. Self-test execution status: ( 249) Self-test routine in progress... 90% of test remaining. Total time to complete Offline data collection: (49272) seconds. Offline data collection capabilities: (0x53) SMART execute Offline immediate. Auto Offline data collection on/off support. Suspend Offline collection upon new command. No 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: ( 30) minutes. SCT capabilities: (0x003d) SCT Status supported. SCT Error Recovery Control supported. SCT Feature Control supported. SCT Data Table supported.
SMART Attributes Data Structure revision number: 1 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 5 Reallocated_Sector_Ct 0x0033 100 100 010 Pre-fail Always - 0 9 Power_On_Hours 0x0032 097 097 000 Old_age Always - 12441 12 Power_Cycle_Count 0x0032 098 098 000 Old_age Always - 1482 177 Wear_Leveling_Count 0x0013 098 098 000 Pre-fail Always - 15 179 Used_Rsvd_Blk_Cnt_Tot 0x0013 100 100 010 Pre-fail Always - 0 181 Program_Fail_Cnt_Total 0x0032 100 100 010 Old_age Always - 0 182 Erase_Fail_Count_Total 0x0032 100 100 010 Old_age Always - 0 183 Runtime_Bad_Block 0x0013 100 100 010 Pre-fail Always - 0 187 Uncorrectable_Error_Cnt 0x0032 100 100 000 Old_age Always - 0 190 Airflow_Temperature_Cel 0x0032 070 065 000 Old_age Always - 30 195 ECC_Error_Rate 0x001a 200 200 000 Old_age Always - 0 199 CRC_Error_Count 0x003e 100 100 000 Old_age Always - 0 235 POR_Recovery_Count 0x0012 099 001 000 Old_age Always - 69 241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always - 2909310200
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% 12441 - # 2 Short offline Completed without error 00% 12441 -
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 255 28175872 28241407 Read_scanning was never started 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.
The first part of the output – the capabilities section – you’ve already seen with the -c option, but the second part is new. The table starting with ID# ATTRIBUTE_NAME FLAG contains the vendor-specific SMART attributes. The column to pay attention to is RAW_VALUE. For SSDs, a good first attribute to examine is in the first row, Reallocated_Sector_Ct, which is the count of reallocated sectors for the drive.
The drive has a pool of sectors held in reserve that can be used to swap out when it encounters bad sectors. If a bad sector is found, the drive allocates a sector from the reserve space, and the data is transferred to this new sector.
Notice that for this drive, the RAW_VALUE is 0. Recall that in the Microsoft study, the attribute is important (Table 1, ReallocSectors). Moreover, after the raw count increases, even by 1, the drive has a high probability of failing relatively soon.
Summary
Pretty much all drives today come with SMART attributes, and the easy-to-configure Linux smartmontools utilities can query these SMART attributes and perform self-tests. However, because SMART attributes are not standard, smartmontools might not be useful for your particular drive (or RAID card), so you should check on the smartmontools mailing list whether your drive is in the database.
A couple of studies have shown that SMART attributes alone cannot predict the failure of drives. Nonetheless, these attributes can be used as indicators to help determine the probability of a drive failing.