[smartmontools-support] Western Digital / SanDisk SSD Media Wear Out Indicator

[Franc Zabkar]

The following thread discusses the Western Digital / SanDisk SSD Media 
Wear Out Indicator as used in model WDS240G2G0A-00JH30:

https://forums.tomshardware.com/threads/ssd-health.3694631/#post-22260328

The Media Wearout Indicator in that example appears to consist of three 
16-bit words -- 0x2506 / 0x0D28 / 0x2506.

I believe these values represent ...

   % wear on a TBW basis
   % wear on a P/E cycle basis
   worst case % wear

Western Digital's SSD Dashboard reports the % wear as 37.06%.

So it would appear that the percentages are encoded as ...

0xabcd -> 0xab . 0xcd %

That is, the upper byte represents the whole decimal percentage (ie 0x25 
= 37%), while the lower byte is the fractional decimal percentage (0x06 
= 0.06%).

The second word, 0x0D28, then converts to 13.40%. The average P/E cycles 
for this particular drive is 67 (= 0x43), so 67 is 13.40% of 500, which 
is a reasonable max P/E cycle spec for 2D TLC NAND.

The SSD in this example would appear to be spec'ed for 100TBW.