QoS, Teardown And Architecture
Teardown
Architecture
The Intel DC P3520 features the standard AIC form factor (above), though 2.5" options are also available. The AIC model requires up to 300LFM of airflow to stay cool, while the 2.5" model requires up to 650LFM. The heatsink consists of a large shroud that covers the face of the device. There is also a smaller dedicated internal heatsink for the proprietary Intel 18-channel controller, and we can see the smaller internal fins poking through when we peer down the internal air channel. Two large capacitors poke up into a hole in the heatsink. The capacitor provides enough power to flush all data in transit to the NAND in the event of a host power loss event.
Intel spread 36 NAND packages out on both sides of the PCB, and there are likely two MLC die per package, which indicates a raw NAND capacity of 2,304GB. At times, Intel will use packages of varying densities to reach various capacity points, so the raw capacity is an unconfirmed measurement. Intel's P Series platform uses LDPC error correction, which is much more powerful than standard BCH ECC and is an important facet of the company's endurance management scheme.
Intel lost some performance due to the reduced die count, so staying with the same number of packages is necesary to minimize the impact. Intel could maintain the same capacity as its previous products with fewer packages by including more of the denser 3D NAND die per package, but this would result in even less parallelism to fuel the controller. IMFT 3D MLC employs a quad-plane design, which means that there are four areas of each die that respond independently to data requests. The quad-plane design increases per-die performance compared to the previous-generation dual-plane planar die.
Thermal pads help to cool the heat-generating components by wicking heat into the heatsink. The design also features five Micron DDR3-1866 DRAM packages, which equates to 2.5GB in an ECC arrangement.
The DC P3520 has all of the features we’ve come to expect from class-leading enterprise SSDs, such as end-to-end data path protection (T10 DIF), a 1 per 10^17 UBER measurement, 2 million hour MTBF, power loss protection (self-test as well), out-of-band management support, AES 256-bit encryption, and advanced thermal throttling. The 2.5” models also support hot plugging.
QoS Specifications
| All values in ms | QD | P3520 2TB (Spec) | P3520 2TB (Our Results) | P3500 2TB | DC P3700 2TB | P3520 450GB | P3520 1.2TB |
|---|---|---|---|---|---|---|---|
| 99% Random Read | 1 | 0.16 | 0.139 | 0.120 | 0.12 | 0.1 | 0.2 |
| 99% Random Read | 128 | 1.1 | 1.352 | 0.75 | 0.750 | 3.5 | 1.4 |
| 99% Random Write | 1 | 0.15 | 0.135 | 0.1 | 0.09 | 0.5 | 0.1 |
| 99% Random Write | 128 | 13 | 12.48 | 18 | 6 | 18 | 13.1 |
| 99.99% Random Read | 1 | 1.8 | 0.201 | 4 | 4 | 0.8 | 0.3 |
| 99.99% Random Read | 128 | 3.0 | 3.28 | 5 | 5 | 6.3 | 3 |
| 99.99% Random Write | 1 | 0.7 | 0.628 | 4 | 0.250 | 4.3 | 0.8 |
| 99.99% Random Write | 128 | 25 | 24.192 | 30 | 15 | 41.2 | 28.3 |
Intel has an intense focus on performance consistency; it was even the first SSD vendor to publish dedicated Quality of Service (QoS) specifications, although others followed. We tested the DC P3520 in CentOS 7 with the 4.7 kernel, which might contribute to some variation from Intel's Windows-derived specifications. Our measurements surpassed Intel's specifications in most workloads, though we did record higher random read 99th and 99.99th percentile measurements.
The DC P3520 has relaxed QoS specifications compared to the previous-generation DC P3500 for the 99th percentile results, but better performance with the more demanding 99.99th percentile specifications. The DC P3700 continues to offer the best QoS measurements, but its refined performance comes with a higher price. Most read-centric workloads do not require such a tight QoS envelope, so the trade off of reduced cost and QoS performance makes sense for mainstream applications.
MORE: How We Test Enterprise SSDs
MORE: How We Test Enterprise HDDs
