Avago Technologies MegaRAID SAS 8204ELP - Manual (Page 21)

Benefits of the SAS Interface 1-7
Copyright © 2007 by LSI Corporation. All rights reserved.
Figure 1.2 Example of an LSI SAS RAID Controller Configured
with an LSISASx12 Expander
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 is a convergence of 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.
SAS controllers leverage a common electrical and physical connection
interface that is compatible with Serial ATA technology. The SAS and
SATA II protocols use a thin, 7-wire connector instead of the 68-wire
LSISASx12
Flash ROM/
NVSRAM/
SRAM
I
2
C/UART
LSISASx12
SAS/SATA II
Drives
PCI Express Interface
SAS/SATA
Drives
SAS/SATA II
Drives
SAS/SATA II
Drives
SAS/SATA II
Drives
8
SRAM
SRAM SDRAM
Peripheral
Bus
72-bit DDR/DDR2
with ECC
Interface
LSISAS1078
PCI Express to SAS ROC
SAS RAID Controller
Expander Expander