The Silicon Motion SM2262EN SSD Controller Preview: Good And Bad Amplified
by Billy Tallis on August 1, 2018 11:45 AM ESTAnandTech Storage Bench - Heavy
Our Heavy storage benchmark is proportionally more write-heavy than The Destroyer, but much shorter overall. The total writes in the Heavy test aren't enough to fill the drive, so performance never drops down to steady state. This test is far more representative of a power user's day to day usage, and is heavily influenced by the drive's peak performance. The Heavy workload test details can be found here. This test is run twice, once on a freshly erased drive and once after filling the drive with sequential writes.
The SM2262EN improves on the SM2262's already class-leading performance on the Heavy test, with an average data rate that is about 12% higher. However, this comes at the cost of reduced performance when the test is run on a full drive—and that was already the biggest weakness of the SM2262 drives.
The average and 99th percentile latencies show an even more stark dichotomy in the SM2262EN's performance characteristics. When the Heavy test is run on a freshly-erased drive, the latency is impressively low and the 99th percentile QoS score is unprecedented. But when the drive fills up, it completely leaves the high-end performance bracket.
Under favorable conditions, the SM2262EN manages to beat the average read latency of the slower Optane SSD, and it offers the top-notch average write latency that the SM2262 drives couldn't quite manage. But when the drive is full, read latency gets pushed to SATA levels and write latency increases by an order of magnitude.
The 99th percentile write latency of the SM2262EN when the Heavy test is run on a freshly-erased drive is less than a third that of any other drive, and the 99th percentile read latency is second only to the Optane SSD 900P. When this drive has plenty of spare area and SLC cache space, it's extremely fast. But fill it up and we're back to low-end NVMe performance that's considerably worse than the 1TB HP EX920.
Energy usage by the SM2262EN drive on the Heavy test is comparable to the SM2262 drives, but with a much bigger disparity between the empty and full drive test runs. Even without the full-drive problems, this wouldn't be the best choice for a laptop.
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Billy Tallis - Wednesday, August 1, 2018 - link
The sustained I/O synthetic tests move far too much data for DRAM caching of user data to have much impact. The burst I/O tests could theoretically benefit from using DRAM as a write cache, but it doesn't look like that's the case based on these results, and I don't think Silicon Motion would really want to add such a complication to their firmware.leexgx - Saturday, August 4, 2018 - link
don't think any SSD has used the DRAM as cache (only used for PAGE table) i could speed things up a little but your still limited by the NAND speed any way, Writing directly to NAND makes more senseMikewind Dale - Thursday, August 2, 2018 - link
That drop in performance in the Heavy test, going from empty to full, was horrifying. I'd like to see some additional tests where the drive gets progressively closer to full. At what point does the drive's performance plummet? Is it gradual or sudden?With other drives, it doesn't matter so much. Most of them have approximately (within 10-20%) the same performance when empty or full, so a person using a full drive will still get approximately the same experience no matter how much they use the drive. But the SM2262EN loses about 80%(!!!!) of its performance when full. So it would be important to know how quickly or gradually this loss occurs as the drive fills.
jjj - Thursday, August 2, 2018 - link
Any chance you are going to the Flash Memory Summit? Might be an interesting year.Billy Tallis - Thursday, August 2, 2018 - link
Yep, we'll be at FMS next week. Tuesday is going to be a very busy day.jjj - Thursday, August 2, 2018 - link
Great, looking forward to your reports!Death666Angel - Thursday, August 2, 2018 - link
Considering this thing is still in a beta state, I don't think any further investigation into the full state performance is beneficial to us consumers. But if a SM2262EN SSD hits the shelves and is buyable, then a look into different states of fullness and the corresponding performance will be greatly appreciated. :D Good test and SSD controller so far.DigitalFreak - Thursday, August 2, 2018 - link
I would definitely like to see this with a retail drive.iwod - Thursday, August 2, 2018 - link
So have we reached peak SSD? If even Optane don't give us any user perceived performance, then surely user would choose larger capacity SSD than 3GB/s vs 2GB/s SSD.Right now we need price to drop faster. 500GB PCI-E SSD with 1GB/s + Speed should be under $100.
rpg1966 - Thursday, August 2, 2018 - link
"Silicon Motion's second-generation NVMe SSD controllers have all but taken over the consumer NVMe SSD market. Drives like the HP EX920 and ADATA SX8200 currently offer great performance at prices that are far lower than what Samsung and Western Digital are charging for their flagship products."This (kind of) implies that the controller is the biggest cost element of a drive. Does anyone have a rough breakdown of parts costs for a drive like this, i.e. controller, DRAM, NAND, and the board+ancillaries?