Specifications

96 IBM Power 770 and 780 Technical Overview and Introduction
controllers is now running 30 SAS bays (six SFF bays in the system unit and twenty-four
2.5-inch bays in the drawer). The disk drawer is attached to the SAS port with a SAS YI cable.
In this 30-bay configuration, all drives must be HDD.
A second unit cannot be cascaded to a EXP24S SFF Gen2-bay Drawer attached in this way.
The EXP24S SFF Gen2-bay Drawer can be ordered in one of three possible
manufacturing-configured MODE settings (not customer set-up) of 1, 2 or 4 sets of disk bays.
With IBM AIX/Linux/VIOS, the EXP 24S can be ordered with four sets of six bays (mode4),
two sets of 12 bays (mode 2), or one set of 24 bays (mode 1). With IBM i, the EXP24S can be
ordered as one set of 24 bays (mode 1).
There are six SAS connectors on the rear of the XP24S SFF Gen2-bay Drawer to which SAS
adapters/controllers are attached. They are labeled T1, T2, and T3, and there are two T1, two
T2, and two T3 (Figure 2-35).
򐂰 In mode 1, two or four of the six ports are used. Two T2 are used for a single SAS
adapter, and two T2 and two T3 are used with a paired set of two adapters or dual
adapters configuration.
򐂰 In mode 2 or mode 4, four ports will be used, two T2 and two T3, to access all SAS bays.
Figure 2-35 EXP24S SFF Gen2-bay Drawer rear connectors
An EXP24S SFF Gen2-bay Drawer in mode 4 can be attached to two or four SAS
controllers and provide a great deal of configuration flexibility. An EXP24S in mode 2 has
similar flexibility. Up to 24 HDDs can be supported with any of the supported SAS
adapters/controllers.
Note: Note the following information:
򐂰 The modes for the EXP24S SFF Gen2-bay Drawer are set by IBM Manufacturing.
There is no option to reset after the drawer has been shipped.
򐂰 If you order multiple EXP24S, avoid mixing modes within that order. There is no
externally visible indicator as to the drawer's mode.
򐂰 Several EXP24S cannot be cascaded on the external SAS connector. Only one #5887
is supported.
򐂰 The Power 770 or Power 780 supports up to 56 XP24S SFF Gen2-bay Drawers.