content_image/985264.jpg content_image/985263.jpg
While you lift and lower the battery during the procedure, grasp the blue handle on each end of the battery and keep the battery parallel to the canister system board, as shown in Figure 12-15. 

<img src='content_image/985264.jpg'>

Important:  During the replacement, the battery must be kept parallel to the canister system board while the battery is removed or replaced. Keep equal force, or pressure, on each end. 

For more information about the BBU replacement process, see IBM Knowledge Center. 

## 12.2.3 Expansion canisters 

For more information about replacement procedures, see this website. 

Two expansion canister slots are on the top of the unit. As with the control enclosure, the left slot is canister 1 and the right slot is canister 2. 

Figure 12-16 shows the rear view of a fully equipped expansion enclosure. 

<img src='content_image/985263.jpg'>

## SAS ports 

SAS ports are used to connect the expansion canister to the node canister or to an extra expansion canister in the chain. Figure 12-17 shows the SAS ports that are on the expansion canister. 

