Performance Focus – 960 PRO 2TB
I think the easiest way to get through these new results for the first time is to just get the charts out there and walk you through them, so here goes. This page is meant to focus on results specific to the subject of the review – in this case, the 960 PRO 2TB.
Before we dive in, a quick note: I’ve been analyzing the effects of how full an SSD is on its performance. I’ve found that most SSDs perform greater when empty (FOB) as they do when half or nearly filled to capacity. Most people actually put stuff on their SSD. To properly capture performance at various levels of fill, the entire suite is run multiple times and at varying levels of drive fill. This is done in a way to emulate actual use of the SSD over time. Random and sequential performance is re-checked on the same areas as additional data is added. Those checks are made on the same files and areas checked throughout the test. Once all of this data is obtained, we again apply the weighting method above in order to balance the results towards the more realistic levels of fill. The below results all use this method.
I'll start you guys off easy. This is sequential performance. The 'Burst' nomenclature denotes the way the workload is applied. The 960 PRO is an MLC-based SSD without any hybrid caching at play, so for this drive, Burst results match Saturated results. I've standardized on Burst as it will better show true performance for the SLC-caching SSDs that we test down the line.
Speeds do look good (3.4 GB/s reads!), though things get a bit wonky at crazy high Queue Depths, likely due to the fact that we had to hack the 950 PRO driver to work with the 960 PRO (long story). Testing the 960 PRO with the Microsoft InBox NVMe driver yielded extremely poor and inconsistent write performance.
Now I'll ease you into random access. The blue and red lines are read and write, and I've thrown in a 70% R/W mix as an additional data point.
Something our readers might not be used to is the noticeably higher write performance at theses lower queue depths. To better grasp the cause, think about what must happen while these transfers are taking place, and what constitutes a ‘complete IO’ from the perspective of the host system.
- Writes: Host sends data to SSD. SSD receives data and acknowledges the IO. SSD then passes that data onto the flash for writing. All necessary metadata / FTL table updates take place.
- Reads: Host requests data from SSD. SSD controller looks up data location in FTL, addresses and reads data from the appropriate flash dies, and finally replies to the host with the data, completing the IO.
The fundamental difference there is when the IO is considered complete. While ‘max’ values for random reads are typically higher than for random writes (due to limits in flash write speeds), lower QD writes can generally be serviced faster, resulting in higher IOPS. Random writes can also ‘ramp up’ faster since writes don’t need a high queue to achieve the parallelism which benefits and results in high QD high IOPS reads.
Our new results have way more data to comb through, so I'm just tossing in some bonus material here. A sampling of the added data we have to choose from, should you feel daring enough to dive into the spaghetti below:
There will be additional data on this page of reviews moving forward, with cool bonuses like a Write Cache Test for those SLC+TLC SSDs. Here's a sample, using the 600p:
Cache size? 16GB. Wasn't that easy?
(man does that thing get stuttery when its cache is full)
Lets move on to the comparisons.