Connecting Expansion Trays
Keep the following points in mind when adding expansion trays to your storage array:
■Expansion trays must be added with power to the array and I/O data transfer turned off. If you need to add an expansion tray to an array that cannot be taken off-line, contact your Sun Technical Support representative before attempting to connect the new tray.
■Controller and expansion trays are shipped with protective plastic plugs in the SAS expansion ports. You must remove these before connecting cables.
■Expansion trays are added serially, in a chain (actually two chains: channel one through the A-side controller and modules, and channel two through the B-side controller and modules). The SAS cable from the expansion port on a controller connects to the In port (Up arrow) on an expansion tray drive module. The SAS cable from a drive module on expansion tray 1 to a corresponding drive module on expansion tray 2 connects from the Out port on expansion tray 1 to the corresponding In port on expansion tray 2. This pattern repeats for each additional drive module on a channel. See FIGURE 2-19for an illustration of this reverse cabling pattern.
■To connect cables for maximum redundancy, controller B must be cabled to the expansion tray B-side modules in the opposite order as the expansion tray A-side modules. That means the last drive module in the A-side chain from controller A must be the first drive module in the B-side chain from controller B. See FIGURE 2-19for an illustration of cabling for maximum tray level redundancy.
■On all SAS cables, affix a label to each end of the cable. See “Drive Module Cable Labeling” on page 47 for labeling tips.
44 Sun StorageTek 2500 Series Array Hardware Installation Guide • March 2007
