IBM ServeRAID-MR10is, User Manual

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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 controller leverages a common electrical and physical connection
interface that is compatible with Serial ATA technology. The SAS
protocols and the 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.
1.5.1 PCI Express Architecture
PCI Express is a local bus system designed to increase data transfers
without slowing down the central processing unit (CPU). You can install
the ServeRAID-MR10is PCI Express SAS/SATA controller in PCI
50 6 32
60 6 32
Table 1.1 Physical Drives Required for Each RAID Level (Cont.)
RAID
Level
Minimum # of
Physical Drives
Maximum # of
Physical Drives