At any given time, you can only have one SCSI cable connected to the JackHammer. To maximize your system's performance, Apple recommends having the JackHammer dedicated to internal SCSI devices and another Ultra Wide SCSI-3 PCI differential card dedicated to external devices.
Note: To ensure error-free operation, only connect one SCSI cable at a time to JackHammers installed in the Workgroup Server 9650. The internal Wide SCSI-3 connector is pre-connected to the drives in your Workgroup Server 9650.