Batteries

Each node canister in a system contains a battery.

The battery within a node supplies power only to that node. If the power to a node canister fails, the node can write its configuration state and cache state to its internal drive using the power provided by the canister battery.

When charged, a canister battery holds enough charge to save the data in the node twice in quick succession. If there is not enough charge in the battery for a node to save its internal state, the node does not start and a critical node error is reported. If battery power drops below the required level while a node is running, it is no longer protected by the battery. The node then safely enters service state while the canister battery recharges.