Importance of Cabling for NVMe Storage Configuration

Sourcing the right cabling for your NVMe PCIe adapter card is of critical importance when planning, building and ultimately maintaining NVMe storage solutions that employ U.2, U.3 or EDSFF form-factor NVMe media, and external enclosures or drive chassis. Proper cabling ensures robust, reliable connectivity, optimal transfer performance, and ease of serviceability.

The following article covers the basics of NVMe cabling solutions, and discusses some of the more common types of connectivity interfaces associated with PCIe NVMe Adapters, storage backplanes, 2.5” & EDSFF NVMe media, and external storage solutions.

Attributes & Features of NVMe Cabling

Performance

NVMe is synonymous with High-Performance, and your choice of cabling solution can make or break the viability of your storage configuration.

The performance of external and 2.5” NVMe storage solutions are heavily dependent on the quality and type of cabling in place. High-quality cables that are designed to minimize latency and maximize available host bandwidth are essential for maximizing data transfer speed. Shoddy design and sub-standard materials are associated with budget cable solutions, and can lead to increased latency, instability and performance loss.

NVMe SSDs perform optimally when allocated x4 lanes of PCIe host bandwidth. If maximizing performance is your goal, you will want to source cables capable of providing x4 lanes for each NVMe SSD.

Scalability

By default, most NVMe cables are already designed to host multiple storage devices; whether via direct connection to the NVMe SSDs (such as an SFF-8639 cable designed for U.2/IU.3 media), or through a backplane, such as an MCIO-to-MCIO connection (SFF-1016).

As such, selecting the right cable can dramatically improve the scalability of an NVMe storage configuration. The ability to support more than one device per connector port, and quickly address the need for more or less storage capacity, provides a high degree of flexibility. This would enable administrators to adapt the storage solution to various applications and workflows, and can help future-proof the solution as storage technology evolves (such as the availability of larger SSDs, or new SSD form factors).

Serviceability and Ease of Maintenance

Professional NVMe cabling solutions typically employ industry-standard connectors, which provide latching systems to ensure a secure, reliable connection between the host computing platform and NVMe storage media. This is especially important for external storage devices, or devices that rely on a portable storage enclosure, such as HighPoint’s SSD6780A. Most quality cables feature quick release latches to improve serviceability in the field. In addition, direct to media cables may include power connectors for the SSDs in order to simplify setup and integration procedures

Hot-Plug / Hot-Swap Capability - Hot-Swap and Hot-Plug capability are essential feature of professional server platform – they enable administrators to safely add or remove individual SSDs without rebooting the OS or powering down the host system. Hot-Swap capable drive bays, when paired with quick release cables are ideal for Hot-Swap capable NVMe Storage solutions, such as HighPoint’s Rocket 1628A and Rocket 7628A PCIe Gen5 x16 NVMe Adapters.

Cabling Applications and Configurations

Supported NVMe Drive Form Factors

While, NVMe drives come in various form factors, NVMe cabling solutions are generally associated with PCIe NVMe Adapter cards designed for use with 2.5” (U.2/U.3) and EDSFF (Enterprise & Datacenter SSD Form Factor) NVMe media. In contrast, M.2 or E1.S SSDs rarely employ device cables, as they are typically connected directly to the host controller itself, such as a system/motherboard’s internal NVMe ports, or to an PCIe NVMe AIC (add-in-card).

PCIe NVMe Adapter Card (HighPoint Rocket 1580 PCIe Gen4 x16 8-Channel NVMe Adapter)

The card features four SFF-8654 ports, each of which provides x8 lanes of PCIe Gen4 bandwidth, and can accept a variety of cabling solutions for U.2 and U.3 SSD configurations.

Direct to Device Configurations

Some NVMe cables are designed to provide a direct connection to the NVMe SSDs. SFF-8639 connectors are employed by industry standard U.2 and U.3 media, while SFF-TA-1002 connectors are often associated with EDSFF media such as E3.S SSDs. Most direct to device cables provide multiple connectors for the SSDs (typically two per cable), and single connector for the host NVMe controller/Adapter. For example, many PCIe Gen4 NVMe Adapters utilize SFF-8654 ports  – you would need an SFF-8654 to SFF-8639 to directly host U.2/U.3 media.

Storage Backplane Configurations

Storage backplanes are generally associated with rackmount storage chassis and mobile rack storage devices. They provide the cabling interface for the PCIe NVMe Adapter/Controller and the NVMe SSDs, which are typically installed into removable 2.5” drive bays. Proper NVMe cabling ensures that these backplanes can support high-speed data transfer to and from each hosted NVMe device. Common backplane connectors include MCIO 8i (SFF-1016) which is suitable for PCIe Gen5 media, SFF-8654 which is ideal for PCIe Gen4 SSDs, SFF-8643 (which is typically used by PCIe 3.0 NVMe Storage backplanes), and OCulink SFF-8611 /SFF-8612,which support PCIe Gen4 / Gen4 backplanes (often for mobile racks).

Server platforms that emply HCI (Hyperconverged Infrastructure) technology (show here: Supermicro’s SYS-211GT-HNC8R) are often paired with PCIe Adapter cards, such as HighPoint’s Rocket 1628A PCIe Gen5 x16 NVMe Switch Adapter, which enable it to host as many as 32 U.2, U.3 or E3.S NVMe SSDs. This pairing would require the use of four SFF-1016 (MCIO 8i) to SFF-1016 cables (such as HighPoint’s CIO8-CIO8-110

External Storage Enclosures

External storage enclosures rely on secure, robust cabling accessories to transfer data to and from the host platform. External NVMe Solutions utilize several types of external cable connectors, chiefly SFF-8644 (for PCIe Gen3 solutions), CDFP 400Gb/s (for PCIe 4.0 solutions) and CDFP 800Gb/s (for PCIe Gen5). These standards are able to support x16 lanes of transfer bandwidth for their respective generation – a hard requirement for customers that need their NVMe storage to deliver maximum performance.

HighPoint’s SSD6780A 8-Bay PCIe 4.0 x8 External NVMe RAID Enclosure utilizes CDFP cables to ensure the solution provides secure, robust host to device PCIe 4.0 x16 connectivity to maximize transfer performance and reliability.

Types of NVMe Cables

There are various types of NVMe cables associated with 2.5” and EDSFF NVMe media, NVMe storage backplanes and external storage enclosures.

SFF-1016 to SFF-8639

SFF-1016	SFF-8639 (with power connector)

This cable type is designed for a host device with SFF-1016 (a.k.a. MCIO) connectivity, and allows it to interface directly with U.2 and U.3 NVMe media, which typically have built-in to SFF-8639 connectors.

SFF-1016 to SFF-1016

SFF-1016	SFF-1016

This cable is designed for SFF-1016 MCIO to MCIO connection (typically from an NVMe PCIe Adapter or controller to an NVMe storage backplane).

SFF-1016 to SFF-1002

	Coming soon
SFF-1016	SFF-TA-1002

This cable type is designed for a host with SFF-1016 (MCIO) connectivity. It provides a direct connection to NVMe media with an SFF-TA-1002 connector (such as an E3.S SSD).

SFF-8654 to SFF-1016

SFF-8654	SFF-1016

This cable bridges SFF-8654 devices (such as a PCIe Gen4 NVMe Adapter card) and a device with an SFF-interfaces (typically the NVMe storage backplane of a rackmount storage chassis).

CDFP 400Gb/s-to CDFP 400Gb/s

Industry standard CDFP (Compact Daughter Card Form-Factor Pluggable) 400Gb/s connectors provide a secure, high-performance PCIe Gen4 x16 host to device connection (good for 4x PCIe Gen4 NVMe SSDs to operate at full speed). HighPoint’s SSD6780A RAID enclosure employs this cable type, and it’s also commonly used with high-speed networking equipment.

SFF-8654 to SFF-8611

SFF-8654	SFF-8611 (OCulink)

This cable is used to connect an SFF-8611 device (OCulink), such as a mobile rack or storage backplane, to an SFF-8654 host (such as a PCIe Gen4 NVMe Adapter card).

SFF-8654 to SFF-8643

SFF-8654	SFF-8643

This cable links an SFF-8654 interface to an SFF-8643 interface (typically a PCIe Gen4 NVMe Adapter or controller to a PCIe 3.0 NVMe storage backplane).

SFF-8654-SFF-8639

SFF-8654	SFF-8639 (with power connector)

Used to connect an SFF-8654 device to an SFF-8639 device. For example, this type of cable is often used to connect PCIe 3.0 U.2/U.3 NVMe SSDs directly to a PCIe Gen4 NVMe Adapter card or controller.

Learn More

HighPoint manufactures an extensive portfolio of datacenter and server-grade NVMe cabling solutions for PCIe Gen5, Gen4 and Gen3 applications. For more information, please visit our NVMe Accessories webpage, or contact Sales@highpoint-tech.com.