Determining SSD Approximate Remaining Lifespan

I couldn’t find anything readily available that was trustworthy or free to determine the lifespan of an SSD. MTBF isn’t very useful as on-time doesn’t wear down like hard disks do. The next best thing is to get the total amount of bytes written to the drive and compare it with benchmark values, from torture tests (write until dead) in particular, that others have done and published.

The total bytes written is recorded within the SMART database of the drive. SmartMonTools is needed to read it. It is cross-platform and free.

https://www.smartmontools.org/wiki/Download

Once installed, start CMD as an administrator (assuming Windows).

C:\WINDOWS\system32>smartctl -a /dev/sda
smartctl 6.5 2016-05-07 r4318 [x86_64-w64-mingw32-win10] (sf-6.5-1)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Device Model: Crucial_CT525MX300SSD4
Serial Number: 16441483025B
LU WWN Device Id: 5 00a075 11483025b
Firmware Version: M0CR031
User Capacity: 525,112,713,216 bytes [525 GB]
Sector Size: 512 bytes logical/physical
Rotation Rate: Solid State Device
Form Factor: < 1.8 inches
Device is: Not in smartctl database [for details use: -P showall]
ATA Version is: ACS-3 T13/2161-D revision 5
SATA Version is: SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Tue Nov 29 23:36:05 2016 PST
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
...
...
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 Reallocated_Sector_Ct 0x0032 100 100 010 Old_age Always - 0
 9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 3
 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 8
171 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 0
172 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 0
173 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 1
174 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 4
183 Runtime_Bad_Block 0x0032 100 100 000 Old_age Always - 0
184 End-to-End_Error 0x0032 100 100 000 Old_age Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
194 Temperature_Celsius 0x0022 066 042 000 Old_age Always - 34 (Min/Max 28/58)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0
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 - 0
202 Unknown_SSD_Attribute 0x0030 100 100 001 Old_age Offline - 0
206 Unknown_SSD_Attribute 0x000e 100 100 000 Old_age Always - 0
246 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 266902214
247 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 8350815
248 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 352002
180 Unused_Rsvd_Blk_Cnt_Tot 0x0033 000 000 000 Pre-fail Always - 1932
210 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 0

We are concerned with three numbers:

  • reallocated sector count
  • sector size – 512
  • total LBA blocks written – 266902214 (in this case, it wasn’t labelled as such; in general, it’s the largest number)

If there are any reallocated sectors, that is bad news as it generally means the drive is on its last legs. Otherwise it can be considered a healthy drive. Multiplying the two numbers yields the total data written in bytes: 512 x 266902214 = 136653933568 bytes or about 127 GB

Referencing various sources on endurance testing, a TLC 240GB drive starts to degrade after 100-1000TB of writes depending on the make. There’s a wide range depending on the generation of technologies (SLC, MLC, TLC) and controllers used.

With the numbers from my SSD, pessimistically, its life is at 127GB / 100TB or 0.1%.

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