IBM ServeRAID M5025, User Manual

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ServeRAID M5025 SAS/SATA Controller Description and Limitations 1-3

SAS Serial SCSI Protocol (SSP), which enables communication with
other SAS devices

SATA II, which enables communication with other SATA II devices

Serial Management Protocol (SMP), which communicates topology
management information directly with an attached SAS expander
device

Serial Tunneling Protocol (STP), which enables communication with
a SATA II device through an attached expander
1.2 ServeRAID M5025 SAS/SATA Controller Description and
Limitations
The ServeRAID M5025 controller is available with eight PHYs. The
controller has one LSISAS2108 ROC (RAID-on-chip) processor that
controls eight external SAS/SATA ports through two x4 SAS external
connectors.
1.2.1 Controller Limitations
The ServeRAID M5025 controller has the following limitations:

You can connect only one device per SAS PHY unless you use an
expander

You can use a maximum cable length of 10 feet (using shorter
cables is preferred)

Cables have to meet the SAS specification

You cannot mix SAS drives and SATA drives in the same virtual disk

You cannot mix SAS or SATA Solid State Drives (SSDs) and legacy
mechanical drives (SAS or SATA) in the same virtual disk

You cannot mix Solid State Drives and Solid State SATA Drives in
the same virtual disk

See Section 3.3.4, “Power Supply Requirements for the ServeRAID
M5025 SAS/SATA Controller,” for information about the power
requirements, and Section 3.3.5, “Operating and Non-operating
Conditions” for information about the minimum and the maximum
temperature ranges