IBM TotalStorage SAN256N Director 2045-N16, Руководство по установке и обслуживанию, Страница: 77 / 157

Chapter 3. Installation
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When a system is powered on, each of the modules runs a Power On Self Test (POST).
If each I/O port has a loopback plug attached, the modules will execute an extended
POST to include running data out of the port(s). To test the system, install 16 loopback
plugs on the first TFIO, run POST, then move the 16 loopback plugs to the next TFIO in
the system. Do this until each I/O port is tested with a loopback plug installed.
External Port Link Rate Test procedure
To run the External Port Link Rate Test, after initial system power up, refer to the IBM
TotalStorage SAN n-type Director Family Enterprise Manager Installation and Operator
Guide (GC26-7720) for information on running the test.
Fiber optic cables
A fiber optic cable is made up of three basic elements:
• Glass fiber, which is the inner core,
• Cladding, which is a special reflective material covering the inner core, and
• A buffer, which is the outer protection layer(s) for the inner core and cladding.
The glass fiber provides the light path, the cladding covers the glass fiber, and the
optical properties of the glass fiber and the cladding junction cause the light to stay
within the glass fiber.
Figure 31. Fiber optic cable diagrams