Percent Lifetime Used attribute for SSDs#
Solid-state drives sound ideal as they have no spinning parts and are very quiet, but they have a limited lifespan as you can’t write a memory cell only an X amount of times. But how to check your SSD on Linux to see if it is still in good shape? S.M.A.R.T. has become the standard for disk health years ago and can be queried by smartctl. So if we query for the health status and show all available attributes we get a good overview.
$ sudo smartctl -AH /dev/sda
smartctl 6.5 2016-05-07 r4318 [x86_64-linux-4.14.8-300.fc27.x86_64] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
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 100 100 000 Pre-fail Always - 0
5 Reallocate_NAND_Blk_Cnt 0x0033 100 100 000 Pre-fail Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 26329
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 164
171 Program_Fail_Count 0x0032 100 100 000 Old_age Always - 0
172 Erase_Fail_Count 0x0032 100 100 000 Old_age Always - 0
173 Ave_Block-Erase_Count 0x0032 010 010 000 Old_age Always - 2708
174 Unexpect_Power_Loss_Ct 0x0032 100 100 000 Old_age Always - 79
180 Unused_Reserve_NAND_Blk 0x0033 000 000 000 Pre-fail Always - 4403
183 SATA_Interfac_Downshift 0x0032 100 100 000 Old_age Always - 0
184 Error_Correction_Count 0x0032 100 100 000 Old_age Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
194 Temperature_Celsius 0x0022 048 036 000 Old_age Always - 52 (Min/Max 21/64)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 16
197 Current_Pending_Sector 0x0032 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 100 100 000 Old_age Always - 1
202 Percent_Lifetime_Used 0x0031 010 010 000 Pre-fail Offline - 90
206 Write_Error_Rate 0x000e 100 100 000 Old_age Always - 0
210 Success_RAIN_Recov_Cnt 0x0032 100 100 000 Old_age Always - 0
246 Total_Host_Sector_Write 0x0032 100 100 000 Old_age Always - 115599678623
247 Host_Program_Page_Count 0x0032 100 100 000 Old_age Always - 2235969936
248 Bckgnd_Program_Page_Cnt 0x0032 100 100 000 Old_age Always - 3472676821
The most interesting attributes are 202 on how much lifetime is left, but also 5, 180, and 9 that show you the number of replaced storage cells and how many hours the disk has been running. If attributes 5 and 180 are changing it is most definitely time to replace this solid-state drive as memory cells have been worn out.