Silicon Motion SM2256 SSD Controller Preview: TLC for Everyone
by Kristian Vättö on June 17, 2015 8:15 AM EST- Posted in
- Storage
- SSDs
- TLC
- Silicon Motion
- SM2256
AnandTech Storage Bench - The Destroyer
The Destroyer has been an essential part of our SSD test suite for nearly two years now. It was crafted to provide a benchmark for very IO intensive workloads, which is where you most often notice the difference between drives. It's not necessarily the most relevant test to an average user, but for anyone with a heavier IO workload The Destroyer should do a good job at characterizing performance. For full details of this test, please refer to this article.
Under a very intensive IO workload, the SMI 2256 is a mediocre performer. Average data rate is high, which suggests good performance at large IO sizes, but the average latency is considerably higher than what MLC drives and the 850 EVO have to offer. Then again, TLC is slower than MLC and 3D TLC, and that's a fact that no controller can get around. Ultimately TLC drives, at least at first, will be more aimed towards typical client workloads anyway, which aren't really illustrated by The Destroyer.
The number of high latency IOs is substantially higher than in the SM2246EN, but at 3.5% it's not alarming especially because the share of >100ms IOs is very moderate and not any worse than MLC drives.
One of the inherent issues with TLC that nobody is talking about is increased power consumption, which our testing proves. TLC requires a higher number of program pulses to program the correct voltage, resulting in longer total program time as well as increased power draw. In addition, SLC caching means that all data essentially gets written twice, which obviously adds power draw despite SLC programming being much more power efficient.
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Death666Angel - Wednesday, June 17, 2015 - link
"I just can't recall a review of a flagship device that wasn't out within 2 weeks of release"Weren't most Note phones, HTC Nexus 9 and Nexus 6 pretty late or only in preview format released? Anandtech is notorious for this stuff when it comes to anything but Apple. :D Though more often than not, eventually we get something.
Michael Bay - Thursday, June 18, 2015 - link
Just two weeks?I`m still waiting for 960 review.
Oxford Guy - Thursday, June 18, 2015 - link
"TLC for everyone?" Maybe if the drives are being given away. The last time I checked MLC isn't that expensive.Oxford Guy - Thursday, June 18, 2015 - link
Samsung has had "some issues" with TLC, eh? Why not specifically state what those are?"Like all TLC SSD designs we have seen, Silicon Motion employs SLC caching in the SM2256 to improve performance and endurance. The size of the SLC cache is configurable by the OEM, but generally the cache size is between 3GB and 12GB depending on the capacity of the drive."
Actual SLC or some sort of simulated SLC?
canthearu - Thursday, June 18, 2015 - link
"Actual SLC or some sort of simulated SLC?"Both the same really. As long as it is dedicated space that will never be asked to perform TLC duty.
Oxford Guy - Saturday, June 20, 2015 - link
Isn't it rather impossible for triple layer NAND to be single layer NAND?DeepStorage - Sunday, June 21, 2015 - link
Most flash foundries have at least some models of their MLC, and TLC flash that can dedicate some percentage of the pages per die to use in SLC mode. It doesn't have quite the performance or endurance of pure SLC but it's close.Oxford Guy - Wednesday, July 15, 2015 - link
" It doesn't have quite the performance or endurance of pure SLC but it's close."Any data on that to link to?
Kristian Vättö - Thursday, June 18, 2015 - link
"TLC for everyone" meaning that now every OEM can build a TLC drive if they wish.SLC cache implementation depends on the NAND. NAND vendors do have special dies with SLC cache functionality (supports a special command set), but so far they haven't sold them to third parties, although I've heard this is about to change. In other cases SLC cache simply means that the controller only writes to the lower pages, which in terms of write performance is about the same as real SLC cache but there is some minor read performance penalty (although I don't know exactly why).
dcaxax - Thursday, June 18, 2015 - link
"admittedly Samsung has had some issues with TLC"That's the understatement of the Millenium. My 840 and 840 Evo have such severe performance degradation (60-70%) that their speed is now visibly impaired and actually compares with some of the fastest HDDs.
Considering the price per GB of an SSD that is completely unacceptable and constitutes a ripoff.
Vendors like Samsung are fobbing off substandard parts supported by immature and unreliable technology to unsuspecting customers.
This is the equivalent of a car with flashy design and big engine which is guaranteed to develop problems as soon as you drive 100 miles. They have a name for it and it's called 'a lemon'.