What is the max speed per lane for PCIe 4.0?
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Title: What is the max speed per lane for PCIe 4.0?
Applicable Products: SSD7000 series
PCIe 4.0 Specifications:
The PCIe Gen4 specification states that each PCIe 4.0 lane (x1) can support up to 2000MB/s.
This translates into a theoretical maximum performance is approximately 2GB/s per lane. For a full x16 lanes, the theoretical transfer rate is 32GB/s.
Real World Gen4 Performance: Platform & Application Factors
The Real world performance of an NVMe storage solution is dependent on many factors:
- The target storage device (Gen4 devices in use; controllers, NVMe media)
- hardware platform (motherboard)
- the source storage device (type of drive/disk), and the type of data (file type, file size, number of files)
- application or benchmark utility used to generate the transfer test
Achieving 32GB/s with a single PCIe 4.0 device is not a realistic goal. Instead, you should look at theoretical performance as a general threshold for an ideal transfer environment.
For example, you would not be able to achieve maximum performance if you were transferring files from a SATA SSD connected to a motherboard’s SATA port, to an NVMe RAID array hosted by an SSD7000 series controller. The performance would be limited (aka bottlenecked) by the performance of the SATA device and SATA interface (around 500-600MB/s max.). While still useful, NVMe storage is overkill for such general-use applications.
NVMe is ideal for transferring files from one high-speed device to another, via a high-performance host interface. For example, if you needed to continuously transfer large files from a separate PCIe 3.0 or 4.0 x16 device, such as uncompressed footage from an HD capture card or high-speed HD camera, a 28,000MB/s + transfer bandwidth is ideal, and may even be required, depending upon the application.
Application/Benchmarking – not all applications are designed to make use of NVMe’s transfer bandwidth. NVMe media, unlike conventional storage, was designed to interface directly with the host system’s CPU (or CPUs). Customers using NVMe storage for standard, day-to-day operations may not notice any significant performance gains, as general use file transfer is largely managed by the operating system’s software caching. Likewise, most of the common benchmark utilities are incapable of truly exercising NVMe media using the default settings. We provide performance testing guides for SSD7000 series controllers, which are available from our Online Knowledge Base: