User`s guide

1-6 Overview

connects up to eight drives either directly or through a port expander.

This configuration is mostly for low-end or entry servers. Enclosure

management is provided through out-of-band I

C bus. Side bands of

both types of internal SAS connectors support the SFF-8485

(SGPIO) interface.

• Midrange internal SAS configurations: This is like the internal

SATA II configurations, but with high-end SAS drives. This is more

suitable for low-range to midrange servers.

• High-end external SAS/SATA II configurations: This configuration

is for external connectivity using SATA II drives, SAS drives, or both.

External enclosure management is supported through in-band,

SCSI-enclosed storage. The configuration must support STP and

SMP.

Figure 1.1 shows a direct-connect configuration. The Inter-IC (I

interface communicates with peripherals. The external memory bus

provides a 32-bit memory bus, parity checking, and chip select signals

for pipelined synchronous burst static random access memory

(PSBRAM), nonvolatile static random access memory (NVSRAM), and

Flash ROM.

Figure 1.1 Example of an LSI SAS Direct-Connect Application

Figure 1.2 shows an example of a SAS RAID controller configured with

an LSISASx12 expander that is connected to SAS drives, SATA II drives,

or both.

Flash ROM/

SAS

PCI Express

RAID Controller

SAS/SATA II Device

32-Bit Memory

Address/Data

Bus

PSBRAM/

SAS/SATA II Device

PCI Express Interface

NVSRAM

Interface