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SATA Express (Serial ATA Express or SATAe) merges PCI Express (PCIe) bandwidth with common SATA connectors. The technology delivers very high performance, while sustaining backwards compatibility with ordinary SATA standards.
One of the driving factors behind SATAe development was to provide higher performance using lower-cost SATA SSDs. SATAe exposes multiple PCIe lanes and two SATA 3.0 (6 Gbps) ports through one host SATAe connector. It supports PCIe storage devices or SATA storage devices, but not both concurrently. SATAe utilizes two lanes with PCIe 2.0 and four lanes with PCIe 3.0.
A good way to think about SATAe is that it's a more advanced, higher-performance SATA standard. It pushes SATA performance for flash SSDs to .6 GBps to .8 GBps with PCIe 2.0 and up to 1.97 GBps for PCIe 3.0.
One indispensable element to the SATAe performance gains comes from taking advantage of PCIe NVM Express. NVMe reduces latency overhead by more than 50%, primarily by eliminating the additional layers of bus abstraction. This non-trivial latency improvement provides a huge boost in SATA performance. Another key to SATAe market acceptance is backwards compatibility with the older SATA cable interface. The SATAe standard specification today is 3.2.
Chipsets for SATAe using PCIe 2.0 and PCIe 3.0 first appeared in 2014 from Intel (X99) and AMD. Most SSD vendors also have SATAe products available today. SATAe narrows the performance gap between small form factor (2.5-inch) flash SSDs and PCIe flash SSDs, but it does not eliminate it. Remember the SATAe connector supports PCIe SSDs or SATA/SATAe SSDs. The PCIe SSDs will still deliver up to twice the performance of SATAe SSDs.
A word of caution: Like many standards, there is room for vendor adherence to vary enough so that not all SATAe interfaces or SSDs are backwards compatible with the older SATA interfaces. Make sure any SATAe implementation meets organizational requirements.
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