U.2 and NVMe - To speed up the PC performance

An important factor for PC performance is the hard disk or SSD that is implemented. Then again, what matters here are two things: the interface technology and the data transfer protocol. In the following the interface U.2 and the data transfer protocol NVMe will be explained in more detail.

After that it will be shown how far U.2 and NVMe play a role for the SSD or, to say it in general words, in which ways these technologies influence the operating speed of the PC. - Finally there are shown some Delock examples of adapters, converters and cable from the U.2 / NVMe product range.

The U.2 interface

The technologies in detail

1. The U.2 interface

U.2 is applied for NVMe SSDs in 2,5" format. Initially, this interface was labeled as SFF-8639. In 2015 the SSD Form Factor Working Group (SFFWG) decided on the simpler name U.2 that also goes well with the established M.2 interface.

In the area of workplace PCs the U.2 interface is not even widely used at present. For conversion there are M.2 to U.2 adapters or PCIe to U.2 plug-in cards available. The converters have a SFF-8643 socket; for connection a suitable U.2 cable with SFF-8639 or SFF-8643 plug has to be used. In contrast to SATA Express, the U.2 interface makes use of additional pins that support the transport of four PCIe lanes.

2. The NVMe protocol

NVM Express ( = NVMe) is a more sophisticated data transfer protocol for the PCIe bus and successor of AHCI (Advanced Host Controller Interface) that was published in 2011 for the first time. NVMe stands for Non-Volatile Memory Express, which means a protocol for persistent storage media. It isn't limited to SSDs but is designed for persistent memory in general.

When NVMe was developed the focus was an optimized command management (submission und completion). Because of the high speed of PCIe SSDs it was also paid attention that as much as possible commands can be processed parallel. Thanks to the more efficient way to distribute commands, the latency (time delay) is significantly reduced. As a result, the sequential read and write performance of data is improved.

To say it simple: the faster the "waiting" CPU can receive data, the sooner these data can be passed on, which means: the faster the PC is working.

In which ways do U.2 and NVMe influence the PC performance?

HDD versus SSD

The working speed of a PC is considerably defined by the storage media on which system software and programs are installed. These days, customary hard disc drives (HDDs) are being replaced by SSDs more and more. SSD stands for Solid State Drive resp. Disc. SSDs have no longer movable mechanical components like HDDs, for example read head or magnetic disc.

Storage processes at SSDs run purely electronical. There are no longer easily damageable engine suspension and read-write-mechanics at SSDs which makes these much more robust and shock-resistant, so SSDs are suitable for mobile applications in particular. Further advantages are very short access times, silent operation, low weight, low power consumption and few waste heat. That's especially important for notebooks and other mobile devices and supports also a long battery life.

SSD and U.2 / NVMe

Classic hard discs, already limited in their memory speed by the mechanical structure, are still using the SATA connector and the AHCI data transfer protocol. As said above, SSDs in itself are considerably faster than HDDs, indeed. But now the used interface technology and data transfer protocol can act as speed brake furthermore. Practically said: SSDs via SAS or SATA that use the AHCI protocol do not reach the speed optimum.

Via SATA connected SSDs with AHCI have data transfer rates up to maximal 0.6 GB/s. SSDs with PCIe-3.0 connector and AHCI get to speeds of about 1 GB/s, once they use one transmission channel ( = 1 lane).

Let's suppose the use of four lanes, the speed would theoretically quadruple and get to 4 GB/s. Practically, that's now made possible by the use of PCIe SSDs which work with the NVMe protocol, whereby the current speed optimum is reached.

DATA TRANSFER RATES BY COMPARISON
Memory Speed
HDD ~ 0,1 GB/s
SSD (AHCI) with SATA connector ~ 0,5 - 0,6 GB/s
SSD (AHCI) with PCIe connector ~ 1 GB/s (1 lane)
SSD (NVMe) with PCI connector ~ 4 GB/s (4 lanes)

Finally, in case a NVMe SSD in 2.5" format shall be applied instead of a plug-in card that can be plugged directly into the M.2 or PCIe slot, the U.2 interface comes into play. In place of the direct way, the PCIe bus can be connected via a U.2 cable. So the support of four PCIe lanes is ensured again.

PCIe SSDs with NVMe provide following

 Large quantity of data are faster transferred
 Operating system boots faster
 Programs start faster
 System react faster

Delock product examples in the area of U.2 and NVMe

Adapters

Adapter M.2 Key M > SFF-8643 NVMe

Connectors:
     1 x 67 Pin M.2 Key M male
     1 x 36 Pin SFF-8643 female
Interface: PCIe (2 or 4 lanes)
Form factor: M.2 2260
Suitable for M.2 Slot with key M based on PCIe
Compatible to PCI Express V3.0
Data transfer rate up to 32 Gbps
Supports NVM Express (NVMe)
Operating temperature: -10 °C ~ 85 °C

PCI Express Card > 1 x internal NVMe M.2 PCIe /
1 x internal SFF-8643 NVMe

Connectors:
     1 x 67 pin M.2 key M slot
     1 x PCI Express x4, V3.0
     1 x 36 pin SFF-8643 female
Interface: PCIe
Supports M.2 modules in format 2280, 2260, 2242 and 2230
      with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.35 mm,
      application of double-sided assembled modules supported
Power supply via PCI Express
Maximum output current: 4 A
Supports NVM Express (NVMe)
Short circuit protection, over heating protection

PCI Express Card > 1 x internal NVMe M.2 PCIe / 1 x internal SFF-8643 NVMe

Connectors:
     1 x 67 pin M.2 key M slot
     1 x PCI Express x4, V3.0
     1 x 36 pin SFF-8643 female
Interface: PCIe
Supports M.2 modules in format 2280, 2260, 2242 and 2230 with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.35 mm, application of double-sided assembled modules supported
Power supply via PCI Express
Maximum output current: 4 A
Supports NVM Express (NVMe)
Short circuit protection, over heating protection

PCI Express x4 Card > 1 x internal SFF-8643 NVMe

Connectors:
     1 x 36 pin SFF-8643 female
     1 x PCI Express x4, V3.0
     1 x 2 pin LED pin header male
Data transfer rate up to 12 Gbps
Supports NVM Express (NVMe)

Converters

PCI Express Card > 1 x internal M.2 NVMe

Connectors:
     1 x 67 pin M.2 key M slot
     1 x PCI Express x4, V3.0
     1 x LED pin header
Interface: PCIe
Supports M.2 modules in format 2280, 2260 and 2242
      with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.5 mm,
      application of double-sided assembled modules supported
Bootable, from UEFI Version 2.3.1
Supports NVM Express (NVMe)

Connectors:
     1 x 67 pin M.2 key M slot
     1 x PCI Express x4, V3.0
     1 x LED pin header
Interface: PCIe
Supports M.2 modules in format 2280, 2260 and 2242 with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.5 mm, application of double-sided assembled modules supported
Bootable, from UEFI Version 2.3.1
Supports NVM Express (NVMe)

Converter U.2 SFF-8639 > M.2 NVMe Key M

Connectors:
     1 x U.2 SFF-8639 male >
     1 x 67 pin M.2 key M slot
Interface: PCIe (2 or 4 lanes)
Supports M.2 modules in format 2280, 2260, 2242 and 2230
      with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.5 mm,
      application of double-sided assembled modules supported
Jumper for 2 or 4 lanes setting M.2 SSD
LEDs for power and activity
Supports NVM Express (NVMe)
Short circuit protection, in-rush current suppression, over heating protection

Connectors:
     1 x U.2 SFF-8639 male >
     1 x 67 pin M.2 key M slot
Interface: PCIe (2 or 4 lanes)
Supports M.2 modules in format 2280, 2260, 2242 and 2230 with key M or key B+M based on PCIe
Maximum height of the components on the module: 1.5 mm, application of double-sided assembled modules supported
Jumper for 2 or 4 lanes setting M.2 SSD
LEDs for power and activity
Supports NVM Express (NVMe)
Short circuit protection, in-rush current suppression, over heating protection

3.5″ Converter SATA 22 pin / SFF-8643 NVMe >
1 x M.2 Key M + 1 x M.2 Key B

Connectors:
     1 x SATA 6 Gb/s 22 pin female (for SATA SSDs)
     1 x 36 pin SFF-8643 female (for PCIe SSDs 2 or 4 lanes)
     1 x 67 pin M.2 key M slot (PCIe SSD)
     1 x 67 pin M.2 key B slot (SATA SSD)
Interface: SATA / PCIe (2 or 4 lanes)
Supports M.2 modules in format 2280, 2260, 2242 and 2230
      with key M or key B+M based on PCIe or SATA
Maximum height of the components on the module: 1.5 mm,
      application of double-sided assembled modules supported
SATA 15 pin power connector always necessary
LEDs for power and activity
Supports NVM Express (NVMe)
Maximum output current: 4 A (PCIe) and 3 A (SATA)

3.5″ Converter SATA 22 pin / SFF-8643 NVMe > 1 x M.2 Key M + 1 x M.2 Key B

Connectors:
     1 x SATA 6 Gb/s 22 pin female (for SATA SSDs)
     1 x 36 pin SFF-8643 female (for PCIe SSDs 2 or 4 lanes)
     1 x 67 pin M.2 key M slot (PCIe SSD)
     1 x 67 pin M.2 key B slot (SATA SSD)
Interface: SATA / PCIe (2 or 4 lanes)
Supports M.2 modules in format 2280, 2260, 2242 and 2230 with key M or key B+M based on PCIe or SATA
Maximum height of the components on the module: 1.5 mm, application of double-sided assembled modules supported
SATA 15 pin power connector always necessary
LEDs for power and activity
Supports NVM Express (NVMe)
Maximum output current: 4 A (PCIe) and 3 A (SATA)

Cables

Cable SFF-8643 male > U.2 SFF-8639 male
+ SATA power connector

Cable SFF-8643 male > U.2 SFF-8639 male + SATA power connector

Connectors:
     SFF-8643 male >
     U.2 SFF-8639 male + SATA 15 pin power connector
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0)
      resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 AWG data line
         24 AWG power line
Length (without connectors):
         Data cable ca. 50 cm
         Power cable ca. 5 cm

Also available as Item 84821 with data cable length ca. 75 cm

Connectors:
     SFF-8643 male >
     U.2 SFF-8639 male + SATA 15 pin power connector
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0) resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 AWG data line
         24 AWG power line
Length (without connectors):
         Data cable ca. 50 cm
         Power cable ca. 5 cm

Also available as Item 84821 with data cable length ca. 75 cm

Cable SFF-8643 male angled > U.2 SFF-8639 male
+ SATA power connector

Cable SFF-8643 male angled > U.2 SFF-8639 male + SATA power connector

Connectors:
     SFF-8643 male angled >
     U.2 SFF-8639 male + SATA 15 pin female
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0)
      resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 + 32 AWG data line
         18 + 24 AWG power line
Length (without connectors):
         Data cable ca. 75 cm
         Power cable ca. 10 cm

Connectors:
     SFF-8643 male angled >
     U.2 SFF-8639 male + SATA 15 pin female
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0) resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 + 32 AWG data line
         18 + 24 AWG power line
Length (without connectors):
         Data cable ca. 75 cm
         Power cable ca. 10 cm

Extension cable U.2 SFF-8639 male > U.2 SFF-8639 female

Connectors:
     U.2 SFF-8639 male >
     U.2 SFF-8639 female
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0)
      resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 AWG data line
         24 AWG power line
Length (without connectors) ca. 50 cm

Also available as Item 84830 with cable length ca. 100 cm

Connectors:
     U.2 SFF-8639 male >
     U.2 SFF-8639 female
Data transfer rate up to 2 GB/s (PCI Express rev. 2.0) resp. 4 GB/s (PCI Express rev. 3.0)
Supports NVM Express (NVMe)
Cable gauge:
         30 AWG data line
         24 AWG power line
Length (without connectors) ca. 50 cm

Also available as Item 84830 with cable length ca. 100 cm

Cable Mini SAS HD SFF-8643 > Mini SAS HD SFF-8643

Connectors:
     Mini SAS HD SFF-8643 male
     Mini SAS HD SFF-8643 male
12 Gb/s Serial Attached SCSI (SAS) specification
Data transfer rate up to 12 Gb/s
Cable gauge: 30 AWG
Cable for internal connection
Cable length (without connectors) ca. 100 cm

Also available as Item 83386 with cable length ca. 50 cm

All Delock U.2 / NVMe products at a glance
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