Avago Technologies MegaRAID SAS 9240-4i - Manual (Page 10)

LSI Corporation
- 10 -
6Gb/s MegaRAID SAS RAID Controllers User Guide
August 2013
Overview
Benefits of the SAS Interface
Figure 1 Example of an LSI SAS Direct-Connect Application
The following figure shows an example of a SAS RAID controller configured with an LSISASx12 expander that is
connected to SAS drives, SATA III drives, or both.
Figure 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, SCSI, and Fibre Channel, and it 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.
Flash ROM/ SAS
PCIe
RAID Controller
SAS/SATA III Device
32-Bit Memory
Address/Data
Bus
PSBRAM/
I 2 C
SAS/SATA III Device
SAS/SATA III Device
SAS/SATA III Device
PCIe Interface
NVSRAM
I 2 C
Interface
LSISASx12
Flash ROM/
NVSRAM/
SRAM
I 2 C/UART
LSISASx12
PCIe Interface
8
SRAM
SRAM SDRAM
Peripheral
Bus
72-bit DDR/DDR2
with ECC
Interface
LSISAS2108
PCIe to SAS ROC
SAS RAID Controller
Expander Expander