[SOLVED] SanDisk Extreme Pro Portable SSD v2 endurance (TBW)

[hmzppz]

Please help me figure out a question I have about SanDisk Extreme Pro Portable SSD v2. Per reviews that I have seen for this drive, it is based on WD SN730E, see e.g.

here (tom's hardware) or here (anandtech).

Also per those reviews, SN730 is supposed be an upgraded version of WD Black SN750 SSD which was used in the previous version of this drive (as well as in WD black P50). Per performance characteristics, this seems to be the case. However, there is no information about the endurance of this drive in the reviews. Just googling, I have found some technical data on WD website

pc-sn730-nvme-ssd

according to which SN730 has a disturbingly low 400TBW endurance for 1TB drive. In comparison, WD Black SN750 has 600TBW endurance for 1TB

wd-black-sn750-nvme-ssd

Can it really be so, that v2 of Extreme Pro SSD has 1.5 times lower endurance than v1 of the same drive at the cost of arguably better performance? Or am I looking at wrong specs?

Please convince me this isn't so (I am having buyer's remorse)

 

[Lutfij]

The way with naming schemes go, the higher the number the better the performance, seeing how the 730 is below the 750, it indicates that it's lower down the order/rank in the company product portfolio.

If you've bought it, then it's best you don't dig any further and dig yourself out of that hole. If you have the option to return it, then well, get something better - grab a Samsung 970 Evo Plus and drop it into an enclosure.

To be fair to WD and almost all SSD's out there, when you skimp out on costs that relate to better prices for the consumer, the SSD's need to have one or more compromises otherwise cream of the crop sort of stuff cost a pretty penny. I will also state that you're looking at the SN730, not the SN730E which is a different SKU. In the world of computing and a vast lineup of hardware, one letter at the end of a product added on could mean 10 things were removed from it to be affordable for you.
^ In fact I bought a Crucial M4 128GB for 150USD back in the day. That's like a high tier 1TB SSD today.

 

[Maxxify]

TBW is just for warrantied writes. It's the same hardware. The SN730 uses BiCS4 in an OEM scheme (static SLC) so should be quite robust.

 

[USAFRet]

"disturbingly low 400TBW endurance "

In your personal use and experience, how much have you written to any of the SSDs you currently own?

For me, the 7 SSD's currently in my system add up to a cumulative ~90TBW. Some of these drives in 24/7 use going back to Nov 2014. 6 years old.
And they don't just shut down at "401 TBW". There were some Intel drives that apparently did this in the past, on purpose, but that is exceedingly rare and not any more.

 

[hmzppz]

"disturbingly low 400TBW endurance "

In your personal use and experience, how much have you written to any of the SSDs you currently own?

For me, the 7 SSD's currently in my system add up to a cumulative ~90TBW. Some of these drives in 24/7 use going back to Nov 2014. 6 years old.
And they don't just shut down at "401 TBW". There were some Intel drives that apparently did this in the past, on purpose, but that is exceedingly rare and not any more.

Thanks, for your reply, it is reassuring. I don't have much personal experience in regard of SSDs, but I was speaking in relative terms as compared to the previous year drive. Wouldn't it also mean that the drive labeled 400TBW is less reliable than the one with 600TBW (at the same capacity)?

 

[hmzppz]

TBW is just for warrantied writes. It's the same hardware. The SN730 uses BiCS4 in an OEM scheme (static SLC) so should be quite robust.

Thanks for your reply, this is what I wanted to hear. But I sill have a couple of questions.
It looks like SN730 uses 96 Layers in BiCS4 vs 64 Layers BiCS3 in SN750. Could those additional layers be the reason for decreased endurance (similirar to QLC vs TLC)? Do I also understand correctly that the manufacturers may rate endurance of the same drive differently when selling to consumers directly vs selling as OEM?

 

[USAFRet]

Thanks, for your reply, it is reassuring. I don't have much personal experience in regard of SSDs, but I was speaking in relative terms as compared to the previous year drive. Wouldn't it also mean that the drive labeled 400TBW is less reliable than the one with 600TBW (at the same capacity)?

Not necessarily.
You also have to note the capacity of the drive.

For instance...the same make/model of a drive, just in different capacities, can/will have vastly different warranty TBW numbers.

ex:
1TB = 200TBW
2TB = 400TBW
4TB = 800TBW

Of the same model line, from the same company.
That number is just for the warranty....just like the 3-5-10 years. You wouldn't expect a drive to simply "stop working" at 3 years + 1 day.
(although, one of my SanDisks died at 33 days past the 3 year warranty. Nothing to do with TBW, though.)

 

[Maxxify]

Thanks for your reply, this is what I wanted to hear. But I sill have a couple of questions.
It looks like SN730 uses 96 Layers in BiCS4 vs 64 Layers BiCS3 in SN750. Could those additional layers be the reason for decreased endurance (similirar to QLC vs TLC)? Do I also understand correctly that the manufacturers may rate endurance of the same drive differently when selling to consumers directly vs selling as OEM?

There are various trade-offs you can make with flash - higher density, better endurance, better performance, etc. This is true of layer changes. The SN730 uses the same density (256Gb) flash but with more layers which suggests larger cells which in turn would have larger voltage capacities and therefore higher endurance. This is not guaranteed as you have to look at die area (these dies are likely smaller, so higher Gb/mm^2) and other factors, but in general if anything the SN730 should have better endurance all else being equal.

 

[mdd1963]

As a point of reference, my Samsung 960 EVO only has 31 TB written thus far after 38-39 months of use...so 'only 400 TBW' should sound a tad more adequate...

 

[hmzppz]

Thanks everyone for your replies. I guess I should stop worrying and start enjoying this nice little drive.