The Toshiba OCZ RD400 (256GB, 512GB, 1TB) M.2 PCIe SSD Review
by Billy Tallis on May 25, 2016 8:02 AM ESTRandom Read Performance
The random read test requests 4kB blocks and tests queue depths ranging from 1 to 32. The queue depth is doubled every three minutes, for a total test duration of 18 minutes. The test spans the entire drive, which is filled before the test starts. The primary score we report is an average of performances at queue depths 1, 2 and 4, as client usage typically consists mostly of low queue depth operations.
There's not a significant random read speed gap between PCIe drives and SATA drives as the unavoidable NAND latency and controller/firmware design matter more than the speed of the host interface. The RD400 performance is a bit odd, with the 512GB RD400 falling behind several SATA drives while the 256GB RD400 is clearly the fastest capacity.
The RD400 again draws significantly more power than the other drives we've measured while the Samsung 950 Pro is a similar load to high-end SATA drives.
 |
|||||||||
The RD400's random read speed scales smoothly with queue depth and unlike the Samsung drives it shows no signs of performance reaching a plateau near the end of the test.
Random Write Performance
The random write test writes 4kB blocks and tests queue depths ranging from 1 to 32. The queue depth is doubled every three minutes, for a total test duration of 18 minutes. The test is limited to a 16GB portion of the drive, and the drive is empty save for the 16GB test file. The primary score we report is an average of performances at queue depths 1, 2 and 4, as client usage typically consists mostly of low queue depth operations.
The Intel 750's enterprise roots show through quite clearly as it delivers the fastest random write speeds, but the RD400 is a strong second place. Samsung's PCIe 3 drives provide only moderate improvement over SATA. This stratification illustrates just how much NVMe drivers, controllers and firmware can differ even when the underlying PCIe link is not clost to full utilization.
In addition to providing better random write speeds than the 950 Pro, the RD400 manages to use a bit less power, giving it a clear efficiency win.
 |
|||||||||
The RD400 reaches full speed by QD4 and maintains it for the rest of the test save for a bit of a drop on the 1TB RD400 near the end as the drive begins to run out of spare area and potentially triggers some thermal throttling.
Facebook
Twitter
RSS
40 Comments
View All Comments
Samus - Wednesday, May 25, 2016 - link
I'm sure a multi billion dollar conglomerate decided to convert the 12v PCIe rail over drawing from the weak 3.3v rail for a reason. Probably something as simple as firmware flashing compatibility. Flashing firmware causes enormous voltage spikes that would easily surpass 10 watts @ 3.3vjjj - Wednesday, May 25, 2016 - link
It's a bit weird to state that the Samsung is the fastest when it loses in write and mixed workloads.Your own benchmark is read heavy but maybe not all readers care most about read perf.
LostWander - Wednesday, May 25, 2016 - link
Read seems to be the most common trait people look for, so if they had to pick one I would agree on that. Kinda odd to give it the title though with no single drive leading in more than a couple benchmarks, it's only "the fastest" in relatively specific categoriesBilly Tallis - Wednesday, May 25, 2016 - link
The Samsung 950 Pro is clearly faster on the ATSB Heavy test which writes more than twice as much data as it reads. If you have a workload that is so much more write heavy that the RD400 comes out ahead, then it's quite atypical and you shouldn't expect our general-audience recommendations to apply.DanNeely - Wednesday, May 25, 2016 - link
If you're mostly writing data that never gets read back again, you're one of the use cases that really still does work well with much cheaper spinning rust.jjj - Wednesday, May 25, 2016 - link
And yet you have more read IOs. Would be interesting to see what you get if you remove at least games and web from that test.Another factor to consider is when you need the perf and when you don't.
I wouldn't buy a drive like this for web browsing or watching video.Would prefer the drive not to choke when you really put pressure on it.
Write is also trailing far behind in data rates and that's not great, do you really like such an unbalanced drive? When your verdict is all about read perf ,maybe a more granular verdict is better. If you would do the math in % for read, write and mixed who wins?
Maybe i am being lazy but can't seem to find any info on multitasking and the system used. Do any of the tests run multiple things at once and are you using an 8 cores? With Zen arriving soon 8 cores/16 threads should become much more popular as the die should be pretty small -y guess somewhere between 99 and 131mm2.
The Samsung feels like a mobile SoC that throttles.Does great when you don't really need the perf but lets you down when you need it. That being said, looking forward to Samsung's new drives (961), on paper those are much better.
Impulses - Wednesday, May 25, 2016 - link
Have you actually used an SM951 or 950 Pro? I've been running one for a while and I don't find the SoC comparison very accurate, mine has a decent amount of airflow going over it (tho it's still near a hot GPU)...AT's own tests proved throttling, when it does happen, wasn't a big deal.
I guess if you're constantly dumping GBs upon GBs of data on one from an equally fast source then yeah, it's gonna be throttle city, but that's not the usage case I see for them.
At least given the current capacity/costs...
jjj - Wednesday, May 25, 2016 - link
You misunderstood, the comparison wasn't about the cause but the effect. Here the weakness is write and mixed workloads but the effect is similar, it lets you down when you need it most.stux - Thursday, May 26, 2016 - link
I use one of the Sm951s in an AngelBird PCI adapter. Takes care of the throttling issue, it never goes above 41C.And it's fantastic :)
theduckofdeath - Wednesday, May 25, 2016 - link
For a consumer PC read performance is nearly infinitely more relevant than random write performance. That's probably why. :)