IBM ServeRAID M5025, User Manual

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Configuration Scenarios 1-5
Specification, Version 1.1 . SATA II is an extension to SATA 1.0a. The
controller supports the following SATA II features:

3 Gbit/s SATA II

Staggered spin-up

Hot plug

Native command queuing

Activity and fault indicators for each PHY

Port Selector (for dual-port drives)
Each port on the ServeRAID M5025 controller supports SAS devices,
SATA II devices, or both using SSP, SMP, STP, and SATA II. SSP
enables communication with other SAS devices. SATA II enables the
controller to communicate with other SATA II devices.
1.4 Configuration Scenarios
There are two main scenarios in which you can use the ServeRAID
M5025 controller:

Low-end, external SATA II configuration: In this configuration, use
the RAID controller as a high-end SATA II compatible controller that
connects up to eight disks 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
2
C bus. Side bands of
both types of external SAS connectors support the SFF-8485
(SGPIO) interface.

Midrange, external SAS configuration: This is like the external
SATA II configuration, but with high-end disks. This is more suitable
for low-range to midrange servers.
Figure 1.1 shows a direct-connect configuration. The Inter-IC (I
2
C)
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.