1-8 Overview
1.5 Benefits of the SAS Interface
SAS is a serial, point-to-point, enterprise-level device interface that
leverages the proven SCSI protocol set. SAS combines the advantages
of SATA II, SCSI, and Fibre Channel, and is the future mainstay of the
enterprise and high-end workstation storage markets. SAS offers a
higher bandwidth per pin than parallel SCSI, and it improves signal and
data integrity.
The SAS interface uses the proven SCSI command set to ensure reliable
data transfers, while providing the connectivity and flexibility of
point-to-point serial data transfers. The serial transmission of SCSI
commands eliminates clock-skew challenges. The SAS interface
provides improved performance, simplified cabling, smaller connectors,
lower pin count, and lower power requirements when compared to
parallel SCSI.
The ServeRAID M5014 and ServeRAID M5015 controllers leverage a
common electrical and physical connection interface that is compatible
with Serial ATA technology. The SAS protocols and SATA II protocols use
a thin, 7-wire connector instead of the 68-wire SCSI cable or 26-wire ATA
cable. The SAS/SATA II connector and cable are easier to manipulate,
allow connections to smaller devices, and do not inhibit airflow. The
point-to-point SATA II architecture eliminates inherent difficulties created
by the legacy ATA master-slave architecture, while maintaining
compatibility with existing ATA firmware.
50 6 32
60 6 32
Table 1.1 Physical Devices Required for Each RAID Level (Cont.)
RAID
Level
Minimum # of
Physical Devices
Maximum # of
Physical Devices
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