Question Endurance drop

[drajitsh]

What has happened to the endurance of M2 SSD in the last half generation. With phison E16 most of the SSD has 1800TBW for 1 TB and 3600 for 2 TB. ( Seagate firecuda 520 had more) . Here is Corsair mp600
https://www.tomshardware.com/reviews/corsair-force-mp600-m2-nvme-ssd
Now they are 700 to 750 TBW for 1 TB. WHAT HAPPENED?

 

[USAFRet]

What has happened to the endurance of M2 SSD in the last half generation. With phison E16 most of the SSD has 1800TBW for 1 TB and 3600 for 2 TB. ( Seagate firecuda 520 had more) . Here is Corsair mp600
https://www.tomshardware.com/reviews/corsair-force-mp600-m2-nvme-ssd
Now they are 700 to 750 TBW for 1 TB. WHAT HAPPENED?

Because the difference between 1800 and 750 is pretty much irrelevant in the consumer space.

In regular use, getting to 25-50% of that 750TBW in a decade is pretty unusual.

 

[Maxxify]

What has happened to the endurance of M2 SSD in the last half generation. With phison E16 most of the SSD has 1800TBW for 1 TB and 3600 for 2 TB. ( Seagate firecuda 520 had more) . Here is Corsair mp600
https://www.tomshardware.com/reviews/corsair-force-mp600-m2-nvme-ssd
Now they are 700 to 750 TBW for 1 TB. WHAT HAPPENED?

TBW is mostly meaningless...

The Phison E12(S) drives also have/had high TBW and changed hardware numerous times. They went from the E12 to the (smaller-packaged) E12S, much less DRAM, and can use multiple types of flash with varying endurance counts. Yet these models kept the same TBW.

Actually, the Phison E16 has a higher failure rate than the E12 and E18, although that's not related to TBW or NAND endurance.

TBW is only valid if you intend to do a certain amount of average writes per day over the course of the warranty period. Not only is 1800TBW insane for a 1TB consumer drive over five years, but it ignores multiple factors. For example, the E16 drives have full-drive SLC caching which actually increases write amplification with regular writes; it's designed for bursty writes (this is one reason enterprise drives have NO SLC caching). Next, actual flash endurance is usually higher than that anyway, on the order of 3000 PEC in general, if all you care about is reliability and not the warranty.

If you are asking generically, "why is it lower," it's because it doesn't need to be high but also because manufacturers change around hardware more commonly now. Additionally, some manufacturers didn't like the Chia and crypto crazes. Also, TBW needs to be properly tracked with write amplification in mind rather than just host writes, but a lot of drives are lazy in reporting. Basically, it's just done for marketing, which is why most drives since 2018 are in the 600-700TBW range per TB.

 

[hotaru.hino]

In the technical sense what happened was in order to increase how much data you can stuff in a flash cell, each flash cell had to be able to store a varying amount of charge in discrete steps. The numbers are purely for example but let's say for single-level cells (SLC), a cell was considered a "1" if it had a voltage of over 1.2V. For multi-level cells (MLC), you could now store 00, 01, 10, and 11, which could correspond to say 0V, 0.4V, 0.8V, and 1.2V. Then we go to triple-level cell (TLC), now we can store 000, 001, 010, 011, 100, 101, 110, and 111, which would correspond to 0V, 0.15V, 0.3V, 0.45V, 0.6V, 0.75V... etc up to 1.2V.

Here's a problem, flash wears out by not being able to flush out all of the charge carriers in the flash cell. So each time you do an erase, some charge carriers remain. Eventually this builds up until the cell can no longer reliably hold a certain lower level of voltage. That's how flash "degrades." By trying to stuff more discrete levels of voltage in a cell, this lowers the amount of charge carriers needed to make the cell unreliable.

So why do this? Because you, the consumer, wanted more storage capacity. The process node flash memory cells are at is similar to processor nodes, so we're pretty much stuffing as many transistors as we physically can. The only way to get more capacity is to allow for more discrete levels of voltage to be used.

 

[drajitsh]

The drives are still TLC

 

[drajitsh]

Because the difference between 1800 and 750 is pretty much irrelevant in the consumer space.

In regular use, getting to 25-50% of that 750TBW in a decade is pretty unusual.

Lots of high end cars have top speeds of more than 250 km/hr even though we almost never drive at that speed. We still like to have that speed.

 

[USAFRet]

Lots of high end cars have top speeds of more than 250 km/hr even though we almost never drive at that speed. We still like to have that speed.

This is not speed, but lifespan:.

Which is better:
10 year 2,000,000 mile warranty
or
10 year 4,000,000 mile warranty

In neither case will you go over the mileage before it ages out.

 

[drajitsh]

This is not speed, but lifespan:.

Which is better:
10 year 2,000,000 mile warranty
or
10 year 4,000,000 mile warranty

In neither case will you go over the mileage before it ages out.

Good point