IBM 4957-J11, Hardware Installation And Maintenance Manual

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The environment in which the enclosure operates must be dust-free to ensure adequate airflow.
Expansion module
IOMs are used in IBM COS Medium and Large Disk Enclosures 12Gb/s storage enclosures.
The figure below is a dimetric rear orientation that shows a pictorial view of an expansion module. You
would revolve the module by 90º along its longitudinal axis, before inserting it into the IOM slot, as shown
in Figure 4 on page 8 and the figure in the section “Removing the IOM” on page 67.
Figure 17. Expansion module - dimetric rear orientation
Each controller module maintains VPD (Vital Product Data) in EEPROM devices, and are interconnected by
I2C buses on the mid-plane. In this way, the modules can discover the type and capabilities of the partner
module(s), and vice versa, within the enclosure. An enclosure system fault occurs when incompatible
configurations are detected. The replacement procedure should be completed within an absolute
maximum of three minutes.
Important:
For a description of EBOD canister LEDs, see Figure 18 on page 20.
12Gb/s expansion module LEDs
The figure and table below provide a description of the expansion module that installs into the rear panel
of an COS Medium/Large JBOD expansion enclosure. The module is shown resting on its base. To install
the module into one of the IOM slots located on the enclosure rear panel, you would first revolve the
module by 90º along its longitudinal axis, before inserting it into a slot as shown in Figure 4 on page 8.
Showing expansion modules separately from the enclosure enables improved clarity in identifying the
component items called out in the diagrams and described in the companion tables within the figure/
table ensembles.
Chapter 3. System overview 19