SSD drives continue to evolve as evident by the release of Intel’s NVMe (Non-Volatile Memory Express) SSD drives. NVMe is a specification that was designed specifically for flash memory communication and allows solid state drives to connect to the system using the PCIe bus, giving these types of Solid State drives the ability to reach their true throughput potential. In addition to being extremely durable, the benefits of NVMe with PCIe over traditional SATA SSD drives are reduced latency, increased IOPS, and even lower power consumption.
As is the case with previous generations, not all SSDs are created equally. Intel NVMe SSD drives use their own engineered and manufactured controller, NAND and firmware which offers improved internal bandwidth as well as reduced internal latencies. Intel offers PCIe/NVMe SSD in two form factors beginning with the AIC form factor which is a PCIe expansion card design. This series is a half height, half length card that plugs directly into a PCIe 3.0 x4 or x8 slot and is ideal for use in low profile servers. The second form factor is a 2.5” U.2 disk drive style that allows you to connect the drive using standard or hot swap drive enclosures.
Performance
SSD drives deliver many benefits for both enterprise and client users, including high performance, extreme durability, and low power consumption. No matter the interface, SSD drives still maintain these inherent characteristics but with NVMe SSD drives users get the benefits of even higher performance mainly measured in IOPS (Input/Output).
As previously mentioned, the Intel NVMe family of drives use the PCIe 3.0 x4 or PCIe 3.0 x 8 (Intel Optane SSD) slot, which delivers up to 4GB/s of throughput for PCIe 3.0 x4, compared to SATA 3 which supports up to 600MB/s data transfer rates. This, however, is not the only limiting legacy technology for traditional SSD drives. In addition, traditional SATA 3 SSD drives utilize the AHCI interface. This communication protocol was designed for high latency mechanical disks and actually resulted in high CPU usage when coupled with low latency SSD drives.
| NVMe | AHCI | |
|---|---|---|
| Latency | 2.8us | 6us |
| Maximum Que Depth | Up to 64K queues with 64K commands each |
Up to 1 queue with 32 commands each |
| Multicore Support | Yes | Limited |
| 4KB Efficiency | One 64B fetch | Two serialized host DRAM fetches required |
Removing the bandwidth limitations of SATA and shedding the AHCI communication protocol with technologies such as NVMe and PCIe that were specifically designed for SSD devices results in dramatically improved performance. When measuring IOPS, Intel NVMe drives are capable of up to 450,000 IOPS, compared to the best performing SATA drives, which could potentially achieve up to 100,000 IOPS. This not only results in higher performance, but also better CPU utilization particularly in applications that have multiple processors.
| Protocol | Intel NVMe | SAS HDD | SATA SSD |
|---|---|---|---|
| Random 4K Read/Write (IOPS) | Up to 450,000 | Up to 190,000 | Up to 100,000 |
| Sequential R/W Performance (MB/s) | Up to 2,800 | Up to 1,000 | Up to 550 |
| Form Factor | 2.5”, HHHL AIC | 2.5” | 2.5” |
| Interface | PCIe 3.0 | SAS 12 GB/s | SATA 6GB/s |