SAS, SCSI and MCIO Drive Cables

Decoding SFF-8087, SFF-8643 and SFF-8654 connectors

Server storage cables are named by connector standard. SFF-8087 is the older internal Mini-SAS plug, SFF-8643 is the denser Mini-SAS HD that carries 12 Gbit/s SAS, SFF-8088 is the external Mini-SAS, and SFF-8654 is SlimSAS, found on newer servers in 4i or 8i versions with four or eight lanes. MCIO is a newer high-speed relative used for PCIe and SAS links. The plugs look alike but are not interchangeable, so match both ends to the controller and the backplane first.

Forward or reverse breakout, and the network cables mixed in

A forward breakout runs from a SAS controller port out to four individual drives, with SFF-8482 ends for SAS drives or SATA ends for SATA drives. A reverse breakout does the opposite, joining four motherboard SATA ports to a single backplane connector. The two look similar but are wired differently, so the wrong one gives no link. SATA drives work on SAS controllers, while SAS drives do not work on SATA ones. This category also holds legacy 68-pin SCSI cables and SFP+ or QSFP+ network cables, which are different products, so read the connector names carefully.

Questions about SAS, SCSI and MCIO Drive Cables

Can I connect SAS drives to a SATA controller?

No. SAS drives need a SAS controller. SATA drives, on the other hand, connect to a SAS controller or backplane, so a SAS setup can mix both drive types, but a SATA setup cannot.

What is the difference between SFF-8087 and SFF-8643?

Both carry four lanes, but SFF-8087 is the older, larger plug and SFF-8643 is the compact Mini-SAS HD plug used for 12 Gbit/s SAS. Adapter cables exist, but you must pick the right plug on each end.

Does a SAS cable need to match my controller speed?

Match it to the controller generation. A cable rated for 12 Gbit/s also runs the slower 3 and 6 Gbit/s rates, so it is the safe pick for newer hardware, provided the plug types fit both ends.