Seagate BARRACUDA ST11950N/ND/W/WD - Manual (Page 34)

Spindle sync reference index signal
(REFSIG+).
J4
SSC
Spindle Sync Cable Connector
(SSC). These pins are used to
connect a spindle sync cable.
Ground (GND).
SCSI
Connector
DC Power
Connector
J01
J4
Pin 1
Pin 2
Figure 11. Spindle sync jumpers and connectors
for ST11950N/ND and ST12550N/ND drives
32 ST11950 and ST12550 Installation Guide, Rev. D
Synchronizing spindles
If you are installing two or more Barracuda drives, you
may (optionally) want to synchronize their spindles to
reduce the latency associated with switching from one
drive to another. Spindle sync cables are used to con-
nect the drives.
For N- and ND-type drives, use pins 1 and 2 on the J4
connector to attach the spindle sync cable. Pin 1
provides the reference index signal (REFSIG+) and
pin 2 provides ground (GND). See Figure 11.