Seagate Cheetah 15K.4 SAS, Product Manual

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46 Cheetah 15K.4 SAS Product Manual, Rev. B
9.2 Dual port support
Cheetah SAS drives have two independent ports. These ports may be connected in the same or different SCSI
domains. Each drive port has a unique SAS address.
The two ports run at the same link rate. The first port to successfully complete speed negotiation sets the link
rate support by both ports. When the second port participates in speed negotiation, it indicates the only sup-
ported speed is the speed selected by the first port. If the first port to complete speed negotiation looses sync
before the second port completes speed negotiation, both ports revert back to the power on condition of allow-
ing either link rate (1.5 or 3.0 Gbits/sec).
Subject to buffer availability, the Cheetah drives support:
• Concurrent port transfers—The drive supports receiving COMMAND, TASK management transfers on both
ports at the same time.
• Full duplex—The drive supports sending XFER_RDY, DATA and RESPONSE transfers while receiving
frames on both ports.