IBM 88861TU Planning Manual page 25

I/O module bay 2
I/O module bay 2 supports an optional I/O module, such as an Ethernet switch or
a pass-thru module, that connects to the two integrated Ethernet controllers in each
of the blade servers.
Note: If you install an I/O module in I/O module bay 2, you will also need to
install an expansion card option, such as the 2/4 Port Ethernet Expansion Card, in
each blade server that will access the external Ethernet network through the switch
module in I/O module bay 2.
I/O module bays 3 and 4
I/O module bays 3 and 4 support SAS connectivity modules or SAS RAID
controller modules.
v If you are using the RAID storage solution, you must install two SAS RAID
controller modules, one in I/O module bay 3 and one in I/O module bay 4. SAS
RAID controller modules require a SAS expansion card option in each blade
server that will access the integrated shared storage.
v If you are using only one SAS connectivity module, install the module in I/O
module bay 3. You can install an additional SAS connectivity module in bay 4. A
SAS connectivity module requires a SAS expansion card option in each blade
server that will access the integrated shared storage.
The two bays also support Ethernet switch modules, Fibre Channel switch
modules, and pass-thru modules (optical and copper) if the storage modules are
not being used.
Important: I/O module bays 3 and 4 must both contain the same type of switch
(either SAS connectivity modules, SAS RAID controller modules, Ethernet switch
modules, pass-thru modules, or Fibre Channel switch modules).
Power modules
The BladeCenter S system supports up to four autoranging power modules that
are capable of supporting either 110 V ac or 220 V ac.
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Chapter 1. Introduction