Mini-Hubs; Servicing Notes; Replacing A Failed Mini-Hub - IBM TotalStorage DS4400 User Manual

Mini-hubs

The mini-hubs are located on the back of the DS4400 Storage Server (see
Figure 52 on page 64). A mini-hub is a single, removable unit that provides the
Fibre Channel interface between a DS4400 Storage Server and hosts or drives.
The back of the DS4400 Storage Server can accommodate eight mini-hubs: up to
four host-side and up to four drive-side mini-hubs. Each mini-hub has two ports. An
SFP module is installed in a mini-hub port; then, a fiber-optic interface cable is
connected into the SFP module. For more information, see "Fibre Channel
connections" on page 4 and "Small Form-Factor Pluggable (SFP) Modules" on page
58.

Servicing notes

Consider the following when servicing mini-hubs:
v You can hot swap (replace) a failed mini-hub while the DS4400 Storage Server is
v Four indicator lights provide status information. If a mini-hub fails, the interface
v If you replace the mini-hub and the SFP modules in them and still experience
For more information, see "Fibre Channel connections" on page 43 and "Interface
ports" on page 145.

Replacing a failed mini-hub

When instructed by the storage-management software, replace a mini-hub. Use the
following procedure to replace either a failed host-side or drive-side mini-hub.
Attention:
that has not failed.
Note: You must remove the fiber-optic cable from the SFP module before you can
1. On the mini-hub that has failed, remove the fiber-optic cables from the SFP
in operation.
fault and the bypass indicator lights on the mini-hub are lit and the loop good
indicator light is off. For more information about indicator lights, see "Mini-hub
indicator lights" on page 33.
problems, the DS4400 Storage Server might have defective components or
connections. Check the storage-management software for indications of other
component failures.
To prevent possible data loss, do not remove cables from a mini-hub
remove the SFP module from the mini-hub port.
modules, as shown in Figure 51 on page 64.
For proper handling of fiber-optic cables, see "Handling fiber-optic cables" on
page 5.
Chapter 3. Replacing DS4400 Storage Server components
63