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

Configuration Scenarios 1-5
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1.4 Configuration Scenarios
There are three main scenarios in which you can use the SAS RAID
controllers:
•
Low-end, internal 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-level servers.
Enclosure management is provided through out-of-band I
2
C bus.
Side bands of both types of internal SAS connectors support the
SFF-8485 (SGPIO) interface.
•
Midrange internal SAS configuration: This configuration is similar
to the internal SATA II configuration, but with high-end disks. This is
more suitable for low-range to midrange servers.
•
High-end external SAS/SATA II configuration: This configuration is
for both internal and 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
2
C)
interface communicates with peripherals. The external memory bus
provides a 32-bit memory bus, parity checking, and chip select signals
for nonvolatile static random access memory (NVSRAM) and Flash
ROM.