The battery within a canister supplies power only to that canister. 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.
The battery is maintained in a charged state by the battery subsystem. In this state, the battery can save critical data and state information in two back-to-back power failures. This means that the node can start immediately after the first power failure without waiting to recharge. After rebooting, if there is not enough charge in the battery for a node to save its internal state, the node remains in service until the battery is charged sufficiently.
If power to a Lenovo Storage® V7000 Gen2 node canister is lost, the system starts to save critical data after a 5-second wait. The saving of critical data runs to completion, even if power is restored during this time. If the power outage is shorter than 5 seconds, the battery continues to support the node and critical data is not saved.
On Lenovo Storage V7000 Gen2 systems, the canister batteries periodically discharge and charge again to maintain the battery life.