The Toshiba OCZ RD400 (256GB, 512GB, 1TB) M.2 PCIe SSD Review
by Billy Tallis on May 25, 2016 8:02 AM ESTMixed Random Read/Write Performance
The mixed random I/O benchmark starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. The queue depth is 3 for the entire test and each subtest lasts for 3 minutes, for a total test duration of 18 minutes. As with the pure random write test, this test is restricted to a 16GB span of the drive, which is empty save for the 16GB test file.
The RD400 sets new records for mixed random I/O performance with a substantial lead over the Intel 750 and Samsung 950 Pro.
The RD400's power consumption is also record setting, but its efficiency is closer to normal for a PCIe SSD on account of the high power consumption yielding high performance.
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Most of the RD400's overall performance advantage is due to strong performance in the final phase of this test where the workload is 100% random writes. The 400GB Intel 750 has even higher random write speed, but performs lower on the other phases of this test.
Mixed Sequential Read/Write Performance
The mixed sequential access test covers the entire span of the drive and uses a queue depth of one. It starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. Each subtest lasts for 3 minutes, for a total test duration of 18 minutes. The drive is filled before the test starts.
The RD400 handles a mixed sequential workload better than anything else and more than twice as fast as SATA drives.
As usual, the RD400 needs plenty of power to deliver its high performance. The Samsung 950 Pro is a bit more efficient despite being slower.
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Performance across the mixed sequential test is usually a bathtub curve with the balanced mixes having the lowest performance. The RD400 bottoms out around the theoretical limit for SATA drives, which is substantially better worst-case performance than anything else. The 950 Pro has much better performance during the pure read start of the test but falls behind in the middle of the test and doesn't bounce back as much at the end.
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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. :)