SSD Wear Leveling Count

I have access to a few non enterprise SSDs running in PCs. The systems are running Linux with different workloads. Most of the SSDs are reporting smart values from the disks, e.g. Wear Leveling Count (WLC) and LBAs written. Taking these two values, it is possible to extrapolate the SSD endurance. The assumption here is, that a wear level count of 100 announces the official end of the SSD life (estimated EOL).

SSD vendor Model Capacity SSD number Gigabytes written WLC Estimated EOL
Samsung 840 EVO(msata) 120GB 5 148 1% 15TB
Samsung 840 EVO(msata) 120GB 5 295 2% 15TB
Samsung 840 EVO(msata) 120GB 5 440 3% 15TB
Samsung 840 EVO(msata) 120GB 5 1100 5% 22TB
 
Samsung 840 EVO 250GB 3 281 1% 28TB
Samsung 840 EVO 250GB 3 589 2% 29TB
Samsung 840 EVO 250GB 3 786 3% 26TB
Samsung 840 EVO 250GB 3 1071 4% 27TB
 
Samsung 840 EVO 500GB 4 567 1% 57TB
Samsung 840 EVO 500GB 4 1149 2% 56TB
Samsung 840 EVO 500GB 4 1714 3% 57TB
Samsung 840 EVO 500GB 4 2175 4% 54TB
Samsung 840 EVO 500GB 4 9700 13% 75TB
Samsung 840 500GB 1 716 2% 35TB
Samsung 840 500GB 1 1075 3% 36TB
Samsung 840 500GB 1 1417 4% 35TB
 
Samsung 840 500GB 2 416 1% 42TB
Samsung 840 500GB 2 857 2% 43TB
Samsung 840 500GB 2 1290 3% 43TB
 
Transcend 370S 1024GB 6 28800 1% 2880TB

The Samsung 840 EVO models have a higher endurance than the non EVO 840 models. The 500 GB Model could reach 56TBytes written. The smaller EVO model with 250GB capacity could reach 28 TBytes written.

The Transcent 370S delives 2 orders of magnitude more Bytes to write by just looking at the SMART numbers. Officially the 1 TB model delivers 1180TBW, my estimate from the SMART numbers says 2880TBW. An interesting point is that the current documentation of Transcent has reduced the lifetime to 400TBW.

Transcent SSD370S

Some charts for Transcent 370S.

Reads and writes from Smart device statistics. Shows Number of 32MByte blocks

The R/W chart shows the number of blocks counted in 32 MB chunks read and written. Host writes and TLC (should be MLC for this disk) writes differ by 10%. When the number of TLC_writes hit 1M, the disc lifetime has fallen from 100% to 99%.

At the same time, the Max erase count reached 100, the avarage erase count 30. Smart has a value Max_Erase_Count_from_Spec which is 3000 for this disk. So 1% of the erase counts have been consumed which is in sync with the disc lifetime. The chart for the erase counts is shown below.

 

Updated: 21/04/2019 — 12:04