How to identify SFF-8470 SAS cable connectors

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SFF-8470 cables come in a variety of configurations. This guide aims to help users identify the various latch types and keying configurations, and the inter-compatibility of each type.

External SAS & SFF-8470

The SFF-8470 connector is an external Serial Attached SCSI (SAS) connector, but the connection itself was adopted by SAS, from the earlier Infiniband specification. There are many vendors that offer SAS/SATA controllers with external SFF-8470 ports, and there are various external storage devices that expose an external SFF-8470 interface. Newer SAS devices with external SAS connectivity are using the SFF-8088 external Mini-SAS connector, which is different again to the SFF-8470 connectors set out below.

SFF-8470 attachment types

The connectors on a SFF-8470 cable are designed to be securely attached to the SFF-8470 device. The SFF-8470 specification defines a connection using thumbscrews, and another using latches, but in practice there are 3 connection types, because there are 2 variants of the latched connector - an ejector-type (pull) latch, and a squeeze-type latch.

These are the 3 attachement types:

 

SFF-8470 keying

The connectors on a SFF-8470 cable may include key-slots, which will mate with their corresponding keys on a SFF-8470 recepticle. Furthermore, the keying configurations vary by the attachment types. If the recepticle on the SFF-8470 device has keys, then the SFF-8470 connector on the cable must have the same keying and attachment type, but if the recepticle does not have keys, then the SFF-8470 connector on the cable does not require (but may still include) key-slots, however the attachment types must still match.

The keying for thumbscrew type attachments is different to the keying for latch type attachments, so a cable with a thumbscrew connector cannot be mated with a latched recepticle, and likewise, a cable with a latched connector cannot be mated with a thumbscrewed recepticle. Furthermore, an ejector-type latched connector requires a compatible recepticle, and a squeeze-type latch requires a compatible recepticle.

The drawings below depict the differences in key-slots on thumbscrew-type connectors, and latch-type connectors, but the differences in latch-type attachments is not shown. Note the key-slot differences... The thumbscrew connector has 4 slots on the upper edge, and 3 slots along the bottom, while the latched connector has 4 slots on the upper edge (in slightly different positions), and 2 slots along the bottom edge.

 

Connections between SFF-8470 devices

Despite the non-matability of various keyed/unkeyed and thumbscrewed/latched cables, it is possible to connect 2 SFF-8470 devices that use different keying/attachment configurations - you just need a cable that has the correct keying/attachment combination on each end of the cable. For example, you can get a cable with a keyed/thumbscrew combination on one end, and a keyed/ejector latch combination on the other.

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We try to make our guides accurate and easy to read. If you've spotted any inaccuracies or you have any suggestions, please let us know. We strive to provide accurate guides, but we not make any warranty about the accuracy or validity, so always consult the operating instructions for your SAS devices.

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