Best SSD Value - Inquiry

[stconquest]

Hello!

 

I spent a lot of yesterday attempting to justify spending more for a second SSD (for reasons).  I currently run a 240GB Corsair Force 3.  I have been using it for about 2.5 years now.  The controller is a Sandforce SF-2281 and the NAND is asynchronous MLC flash memory.

 

This drive is still fast enough (general use) and I hope it lasts longer.  I am in need of another though.  Looking at the Canadian market, what is really the best value?  Is a $75 SP550 (TLC, SM controller) that much worse than a $115 Samsung EVO (TLC (3D NAND), Samsung controller)?

 

If I bought right now, I would probably want to take a risk on the Silicon Motion controller of the Sandisk Z400 (MLC NAND) for $85, but man is it ever sluggish.

 

I will gladly trade off some speed/sluggishness for long term reliability (sustained speed over time).

 

Is TLC really that bad?  How does the Samsung 850 EVO get away with TLC flash memory in their drive?

 

For reference, the Canadian SSD market (240GB+):  http://ca.pcpartpicker.com/parts/internal-hard-drive/#t=0&S=230000,10000000&sort=a10&page=1

[ChrisCross]

6 minutes ago, stconquest said:

...

if you take a look at the speeds it doesnt make a hugh difference. the samsung is a way better driver but we are hitting the limits of sata3 with most modern drives so it doesnt make a huge difference.

pcie nvme needs to be more effordable for the annoying sata standart to finally die.

[stconquest]

7 minutes ago, ChrisCross said:

if you take a look at the speeds it doesnt make a hugh difference. the samsung is a way better driver but we are hitting the limits of sata3 with most modern drives so it doesnt make a huge difference.

pcie nvme needs to be more effordable for the annoying sata standart to finally die.

I am mainly concerned with sustained speeds over time:  If my drive is XXX speed the day I buy it, I want it to stay at that speed until it dies.  It is why my post is focused on controllers and TLC vs MLC flash memory.

 

I hear TLC memory has a performance drop off over time.  I am assuming a wipe of the drive (TLC) will solve any voltage drift issues.  Is this correct?  (question is to anyone).

 

My brain is mushy.  That is why I made this thread.  Too much seemingly random information that I really don't understand. 

[ChrisCross]

Just now, stconquest said:

...

i honestly dont know about the long term speeds of the adata.

 

wiping the drive could help but im not quite sure. it could also be the wear of the memory chips that is causing those issues. if thats the case it just depends on how much is written to the drive totally and there is no way to "refresh" the drive like with a traditional hdd.

[Sakkura]

30 minutes ago, stconquest said:

I will gladly trade off some speed/sluggishness for long term reliability (sustained speed over time).

 

Is TLC really that bad?  How does the Samsung 850 EVO get away with TLC flash memory in their drive?

TLC isn't bad in general, it depends on the particular NAND as well as how the SSD uses it.

 

The 850 Evo uses 3D NAND, which lets them cram in a lot of memory cells without making them very small in the 2D plane; it's built on an old 40nm node, where planar (2D) NAND has gone below 20nm now. The smaller you make the memory cells, the more you run into issues with write endurance and voltage drift, eventually affecting performance as well. So the "reset" to 40nm with 3D is super-welcome. But 3D is tough, so Samsung has had a bit of a monopoly on that tech. But Micron/Crucial is now finally jumping into the fray, with the upcoming MX300.

 

Anyway... TLC means squeezing 3 bits of information into each memory cell. That makes it more sensitive to voltage drift, which can exacerbate the problems you run into with smaller process nodes. This is what caused the slowdown issue on the Samsung 840 and 840 Evo, and it's probably also why newer TLC drives from Crucial and OCZ have performed so poorly. Going 3D allowed Samsung to avoid those problems and still make a fairly affordable SSD with high performance.

 

The A-Data SP550 is one of the 2D TLC drives, so it is sort of in the same category as the Crucial BX200 and OCZ Trion 100 and 150. But it's not exactly the same drive, so its particular characteristics are different - in this case, significantly better overall. Still not as good as the 850 Evo, but whether the latter is worth the premium is difficult to say.

[stconquest]

29 minutes ago, Sakkura said:

TLC isn't bad in general, it depends on the particular NAND as well as how the SSD uses it.

 

The 850 Evo uses 3D NAND, which lets them cram in a lot of memory cells without making them very small in the 2D plane; it's built on an old 40nm node, where planar (2D) NAND has gone below 20nm now. The smaller you make the memory cells, the more you run into issues with write endurance and voltage drift, eventually affecting performance as well. So the "reset" to 40nm with 3D is super-welcome. But 3D is tough, so Samsung has had a bit of a monopoly on that tech. But Micron/Crucial is now finally jumping into the fray, with the upcoming MX300.

 

Anyway... TLC means squeezing 3 bits of information into each memory cell. That makes it more sensitive to voltage drift, which can exacerbate the problems you run into with smaller process nodes. This is what caused the slowdown issue on the Samsung 840 and 840 Evo, and it's probably also why newer TLC drives from Crucial and OCZ have performed so poorly. Going 3D allowed Samsung to avoid those problems and still make a fairly affordable SSD with high performance.

 

The A-Data SP550 is one of the 2D TLC drives, so it is sort of in the same category as the Crucial BX200 and OCZ Trion 100 and 150. But it's not exactly the same drive, so its particular characteristics are different - in this case, significantly better overall. Still not as good as the 850 Evo, but whether the latter is worth the premium is difficult to say.

I don't mind paying the $40 more, but if I don't see a difference in my day-to-day use I won't.  Spending the $75 and getting 5-10 years out of the drive is a good deal.  The SP550 will last longer than that though.

[stconquest]

Found a Patriot Ignite (240GB) for $92, picked it up.  Phison controller - MLC Asychronous NAND.  All in, $104 to my door.