IBM N series Hardware Manual page 162

Before you begin, verify that the following prerequisites were met:
You ordered and received the appropriate type, number, and length of SAS optical cables
that are required for your configuration.
Your ordered and received the appropriate number and type of SAS HBAs for each
controller.
Each controller requires two SAS ports for each stack to which it is connected. For
example, one stack at Site 1 and one stack as Site 2 requires four ports on each controller.
You installed the SAS HBAs in Step 9 of this procedure after you halt your system.
For more information about SAS ports, see the Universal SAS and ACP Cabling Guide.
You must download the Universal SAS and ACP Cabling Guide from the N series Support
Site.
Disk shelves that are connected with SAS optical cables require a version of disk shelf
firmware that supports SAS optical cables.
Best practice is to update all disk shelves in the storage system with the latest version of
disk shelf firmware.
Note: Do not revert disk shelf firmware to a version that does not support SAS optical
cables.
Commands are entered at the console of either controller, unless otherwise noted.
This procedure assumes that you are replacing bridges and SAS copper cables on all
stacks on your system.
You replace bridges and cables one stack at a time.
You cannot change any disks, disk shelves, or components of a controller module as part
of this procedure.
Figure 9-6 on page 143 shows a stretch MetroCluster system with FibreBridge 6500N
bridges and SAS copper cables which can be used as a reference when planning their
replacement.
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IBM System Storage N series Hardware Guide