The Toshiba XG6 1TB SSD Review: Our First 96-Layer 3D NAND SSD
by Billy Tallis on September 6, 2018 8:15 AM ESTAnandTech Storage Bench - Light
Our Light storage test has relatively more sequential accesses and lower queue depths than The Destroyer or the Heavy test, and it's by far the shortest test overall. It's based largely on applications that aren't highly dependent on storage performance, so this is a test more of application launch times and file load times. This test can be seen as the sum of all the little delays in daily usage, but with the idle times trimmed to 25ms it takes less than half an hour to run. Details of the Light test can be found here. As with the ATSB Heavy test, this test is run with the drive both freshly erased and empty, and after filling the drive with sequential writes.
The average data rates delivered by the Toshiba XG6 on the Light test are similar to many other high-end NVMe SSDs though clearly lower than the fastest tier of drives. As with the Heavy test, the full-drive performance is the more significant improvement from the XG5.
Average latency from the XG6 has improved for both full and empty drive test runs, but the 99th percentile latency when the Light test is run on a freshly erased drive is actually worse than the XG5.
Average read latency doesn't vary much among high-end NVMe SSDs, though there are some outliers for full-drive read latency. The XG6 doesn't have the best scores, but the improvements the XG6 brings over the XG5 help ensure it doesn't stick out even among the newest and fastest competitors. For average write latency, the improvement in full-drive performance secures the XG6 a position in the high-end tier.
The 99th percentile read latency from the XG6 is typical for a high-end SSD when the Light test is run on an empty drive but a little high when the drive is full, though it's still improved over the XG5. The 99th percentile write latency regressed significantly for the empty-drive test run, back to the level of old high-end drives or current entry-level NVMe, but the full-drive 99th percentile write latency is excellent.
The energy used by the XG6 over the course of the Light test is barely different from that used by the XG5 or the WD Black. All three are slightly less efficient than the Crucial MX500 mainstream SATA drive and some of the more efficient entry-level NVMe drives.
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Spoelie - Thursday, September 6, 2018 - link
2 short questions:- what happened to the plextor M9Pe, performance is hugely different from the review back in march.
- i know this is already the case for a year or so, but what happened to the perf consistency graphs, where can i deduce the same information from?
hyno111 - Thursday, September 6, 2018 - link
M9Pe had firmware updates, not sure if it's applied or related though.DanNeely - Thursday, September 6, 2018 - link
I don't recall the details, but something went wrong with generating the performance consistency data, and they were pulled pending finding a fix due to concerns they were no longer valid. IF you have the patience to dig through the archive, IIRC the situation was explained in the first review without them.Billy Tallis - Thursday, September 6, 2018 - link
I think both of those are a result of me switching to a new version of the test suite at the same time that I applied the Spectre/Meltdown patches and re-tested everything. The Windows and Linux installations were updated, and a few tweaks were made to the synthetic test configuration (such as separating the sequential read results according to whether the test data was written sequentially or randomly). I also applied all the drive firmware updates I could find in the April-May timeframe.The steady-state random write test as it existed a few years ago is gone for good, because it really doesn't say anything relevant about drives that use SLC caching, which is now basically every consumer SSD (except Optane and Samsung MLC drives). I also wasn't too happy with the standard deviation-based consistency metric, because I don't think a drive should be penalized for occasionally being much faster than normal, only much slower than normal.
To judge performance consistency, I prefer to look at the 99th percentile latencies for the ATSB real-world workload traces. Those tend to clearly identify which drives are subject to stuttering performance under load, without exaggerating things as much as an hour-long steady-state torture test.
I may eventually introduce some more QoS measures for the synthetic tests, but at the moment most of them aren't set up to produce meaningful latency statistics. (Testing at a fixed queue depth leads to the coordinated omission problem, potentially drastically understating the severity of things like garbage collection pauses.) At some point I'll also start graphing the performance as a drive is filled, but with the intention of observing things like SLC cache sizes, not for the sake of seeing how the drive behaves when you keep torturing it after it's full.
I will be testing a few consumer SSDs for one of my upcoming enterprise SSD reviews, and that will include steady-state full drive performance for every test.
svan1971 - Thursday, September 6, 2018 - link
I wish current reviews would use current hardware, the 970 Pro replaced the 960 Pro months ago.Billy Tallis - Thursday, September 6, 2018 - link
I've had trouble getting a sample of that one; Samsung's consumer SSD sampling has been very erratic this year. But the 970 Pro is definitely a different class of product from a mainstream TLC-based drive like the XG6. I would only include 970 Pro results here for the same reason that I include Optane results. They're both products for people who don't really care about price at all. There's no sensible reason to be considering a 970 Pro and an XG6-like retail drive as both potential choices for the same purchasing decision.mapesdhs - Thursday, September 6, 2018 - link
Please never stop including older models, the comparisons are always useful. Kinda wish the 950 Pro was in there too.Spunjji - Friday, September 7, 2018 - link
I second this. I know that I am (and feel most other savvy consumers would be) more likely to compare an older high-end product to a newer mid-range product, partly to see if it's worth buying the older gear at a discount and partly to see when there is no performance trade-off in dropping a cost tier.jajig - Friday, September 7, 2018 - link
I third it. I want to know if an upgrade is worth while.dave_the_nerd - Sunday, September 9, 2018 - link
Very much this. And not all of us upgrade our gear every year or two.